diff --git a/fixtures/scheduler/index.html b/fixtures/scheduler/index.html
index 5da9d66163010..4bc57fbd9a7cf 100644
--- a/fixtures/scheduler/index.html
+++ b/fixtures/scheduler/index.html
@@ -91,19 +91,8 @@ <h2>Tests:</h2>
       <div> If the counter advanced while you were away from this tab, it's correct.</div>
     </li>
     <li>
-      <p>Can pause execution, dump scheduled callbacks, and continue where it left off</p>
-      <button onClick="runTestEight()">Run Test 8</button>
-      <div><b>Click the button above, press "continue" to finish the test after it pauses:</b></div>
-      <button onClick="continueTestEight()">continue</button>
-      <div><b>Expected:</b></div>
-      <div id="test-8-expected">
-      </div>
-      <div> -------------------------------------------------</div>
-      <div> If the test didn't progress until you hit "continue" and </div>
-      <div> you see the same above and below afterwards it's correct.
-        <div> -------------------------------------------------</div>
-        <div><b>Actual:</b></div>
-        <div id="test-8"></div>
+      <p>Test Eight Removed</p>
+      <p>Test 8 was removed because it was testing a feature that was removed from the scheduler.</p>
     </li>
     <li>
       <p>Can force a specific framerate</p>
@@ -156,9 +145,6 @@ <h2>Tests:</h2>
   unstable_scheduleCallback: scheduleCallback,
   unstable_cancelCallback: cancelCallback,
   unstable_now: now,
-  unstable_getFirstCallbackNode: getFirstCallbackNode,
-  unstable_pauseExecution: pauseExecution,
-  unstable_continueExecution: continueExecution,
   unstable_forceFrameRate: forceFrameRate,
   unstable_shouldYield: shouldYield,
   unstable_NormalPriority: NormalPriority,
@@ -587,50 +573,6 @@ <h2>Tests:</h2>
   scheduleCallback(NormalPriority, incrementCounterAndScheduleNextCallback);
 }
 
-function runTestEight() {
-  // Test 8
-  // Pauses execution, dumps the queue, and continues execution
-  clearTestResult(8);
-
-  function countNodesInStack(firstCallbackNode) {
-    var node = firstCallbackNode;
-    var count = 0;
-    if (node !== null) {
-      do {
-        count = count + 1;
-        node = node.next;
-      } while (node !== firstCallbackNode);
-    }
-    return count;
-  }
-
-  scheduleCallback(NormalPriority, () => {
-
-    // size should be 0
-    updateTestResult(8, `Queue size: ${countNodesInStack(getFirstCallbackNode())}.`);
-    updateTestResult(8, 'Pausing... press continue to resume.');
-    pauseExecution();
-
-    scheduleCallback(NormalPriority, function () {
-      updateTestResult(8, 'Finishing...');
-      displayTestResult(8);
-    })
-    scheduleCallback(NormalPriority, function () {
-      updateTestResult(8, 'Done!');
-      displayTestResult(8);
-      checkTestResult(8);
-    })
-
-    // new size should be 2 now
-    updateTestResult(8, `Queue size: ${countNodesInStack(getFirstCallbackNode())}.`);
-    displayTestResult(8);
-  });
-}
-
-function continueTestEight() {
-  continueExecution();
-}
-
 function runTestNine() {
   clearTestResult(9);
   // We have this to make sure that the thing that goes right after it can get a full frame
diff --git a/packages/react-dom-bindings/src/client/validateDOMNesting.js b/packages/react-dom-bindings/src/client/validateDOMNesting.js
index 49d8b5c158f62..d6fdc5e857ed3 100644
--- a/packages/react-dom-bindings/src/client/validateDOMNesting.js
+++ b/packages/react-dom-bindings/src/client/validateDOMNesting.js
@@ -297,6 +297,8 @@ function isTagValidWithParent(tag: string, parentTag: ?string): boolean {
         tag === 'hr' ||
         tag === 'option' ||
         tag === 'optgroup' ||
+        tag === 'script' ||
+        tag === 'template' ||
         tag === '#text'
       );
     case 'optgroup':
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.js b/packages/react-reconciler/src/ReactFiberWorkLoop.js
index a71eb543cfe5d..7377f605a8811 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.js
@@ -32,7 +32,6 @@ import {
   enableSchedulingProfiler,
   enableUpdaterTracking,
   enableTransitionTracing,
-  useModernStrictMode,
   disableLegacyContext,
   alwaysThrottleRetries,
   enableInfiniteRenderLoopDetection,
@@ -4205,7 +4204,7 @@ function commitDoubleInvokeEffectsInDEV(
   hasPassiveEffects: boolean,
 ) {
   if (__DEV__) {
-    if (useModernStrictMode && (disableLegacyMode || root.tag !== LegacyRoot)) {
+    if (disableLegacyMode || root.tag !== LegacyRoot) {
       let doubleInvokeEffects = true;
 
       if (
diff --git a/packages/react-reconciler/src/__tests__/ActivityStrictMode-test.js b/packages/react-reconciler/src/__tests__/ActivityStrictMode-test.js
index 85365d3e708fc..12b319080de5c 100644
--- a/packages/react-reconciler/src/__tests__/ActivityStrictMode-test.js
+++ b/packages/react-reconciler/src/__tests__/ActivityStrictMode-test.js
@@ -77,7 +77,7 @@ describe('Activity StrictMode', () => {
     ]);
   });
 
-  // @gate __DEV__ && enableActivity && useModernStrictMode
+  // @gate __DEV__ && enableActivity
   it('should not trigger strict effects when offscreen is hidden', async () => {
     await act(() => {
       ReactNoop.render(
diff --git a/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js b/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js
index 0ce01a650c323..0c7e75c39a4a5 100644
--- a/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js
+++ b/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js
@@ -945,34 +945,25 @@ describe('StrictEffectsMode', () => {
       shouldSuspend = false;
     });
 
-    if (gate(flags => flags.useModernStrictMode)) {
-      expect(log).toEqual([
-        'Child rendered',
-        'Child rendered',
-        // !!! Committed, destroy and create effect.
-        // !!! The other effect is not destroyed and created
-        // !!! because the dep didn't change
-        'Child dep destroy',
-        'Child dep create',
-
-        // Double invoke both effects
-        'Child destroy',
-        'Child dep destroy',
-        'Child create',
-        'Child dep create',
-        // Fires setState
-        '-----------------------after setState',
-        'Child rendered',
-        'Child rendered',
-        'Child dep create',
-      ]);
-    } else {
-      expect(log).toEqual([
-        'Child rendered',
-        'Child rendered',
-        'Child dep destroy',
-        'Child dep create',
-      ]);
-    }
+    expect(log).toEqual([
+      'Child rendered',
+      'Child rendered',
+      // !!! Committed, destroy and create effect.
+      // !!! The other effect is not destroyed and created
+      // !!! because the dep didn't change
+      'Child dep destroy',
+      'Child dep create',
+
+      // Double invoke both effects
+      'Child destroy',
+      'Child dep destroy',
+      'Child create',
+      'Child dep create',
+      // Fires setState
+      '-----------------------after setState',
+      'Child rendered',
+      'Child rendered',
+      'Child dep create',
+    ]);
   });
 });
diff --git a/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js b/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js
index c9f65a20a0c7b..5829cd0904266 100644
--- a/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js
@@ -461,7 +461,6 @@ describe('StrictEffectsMode defaults', () => {
       expect(log).toEqual([]);
     });
 
-    //@gate useModernStrictMode
     it('disconnects refs during double invoking', async () => {
       const onRefMock = jest.fn();
       function App({text}) {
diff --git a/packages/react-server-dom-webpack/src/__tests__/ReactFlightDOMReplyEdge-test.js b/packages/react-server-dom-webpack/src/__tests__/ReactFlightDOMReplyEdge-test.js
index 0c6ec9599e1e2..f6157dff171d7 100644
--- a/packages/react-server-dom-webpack/src/__tests__/ReactFlightDOMReplyEdge-test.js
+++ b/packages/react-server-dom-webpack/src/__tests__/ReactFlightDOMReplyEdge-test.js
@@ -245,4 +245,31 @@ describe('ReactFlightDOMReplyEdge', () => {
       ),
     );
   });
+
+  it('should abort when parsing an incomplete payload', async () => {
+    const infinitePromise = new Promise(() => {});
+    const controller = new AbortController();
+    const promiseForResult = ReactServerDOMClient.encodeReply(
+      {promise: infinitePromise},
+      {
+        signal: controller.signal,
+      },
+    );
+    controller.abort();
+    const body = await promiseForResult;
+
+    const decoded = await ReactServerDOMServer.decodeReply(
+      body,
+      webpackServerMap,
+    );
+
+    let error = null;
+    try {
+      await decoded.promise;
+    } catch (x) {
+      error = x;
+    }
+    expect(error).not.toBe(null);
+    expect(error.message).toBe('Connection closed.');
+  });
 });
diff --git a/packages/react-server/src/ReactFlightReplyServer.js b/packages/react-server/src/ReactFlightReplyServer.js
index 930998ea3d889..4db7571bb66a6 100644
--- a/packages/react-server/src/ReactFlightReplyServer.js
+++ b/packages/react-server/src/ReactFlightReplyServer.js
@@ -169,6 +169,8 @@ export type Response = {
   _prefix: string,
   _formData: FormData,
   _chunks: Map<number, SomeChunk<any>>,
+  _closed: boolean,
+  _closedReason: mixed,
   _temporaryReferences: void | TemporaryReferenceSet,
 };
 
@@ -255,6 +257,14 @@ function createResolvedModelChunk<T>(
   return new Chunk(RESOLVED_MODEL, value, id, response);
 }
 
+function createErroredChunk<T>(
+  response: Response,
+  reason: mixed,
+): ErroredChunk<T> {
+  // $FlowFixMe[invalid-constructor] Flow doesn't support functions as constructors
+  return new Chunk(ERRORED, null, reason, response);
+}
+
 function resolveModelChunk<T>(
   chunk: SomeChunk<T>,
   value: string,
@@ -493,6 +503,8 @@ function initializeModelChunk<T>(chunk: ResolvedModelChunk<T>): void {
 // Report that any missing chunks in the model is now going to throw this
 // error upon read. Also notify any pending promises.
 export function reportGlobalError(response: Response, error: Error): void {
+  response._closed = true;
+  response._closedReason = error;
   response._chunks.forEach(chunk => {
     // If this chunk was already resolved or errored, it won't
     // trigger an error but if it wasn't then we need to
@@ -514,6 +526,10 @@ function getChunk(response: Response, id: number): SomeChunk<any> {
     if (backingEntry != null) {
       // We assume that this is a string entry for now.
       chunk = createResolvedModelChunk(response, (backingEntry: any), id);
+    } else if (response._closed) {
+      // We have already errored the response and we're not going to get
+      // anything more streaming in so this will immediately error.
+      chunk = createErroredChunk(response, response._closedReason);
     } else {
       // We're still waiting on this entry to stream in.
       chunk = createPendingChunk(response);
@@ -1082,6 +1098,8 @@ export function createResponse(
     _prefix: formFieldPrefix,
     _formData: backingFormData,
     _chunks: chunks,
+    _closed: false,
+    _closedReason: null,
     _temporaryReferences: temporaryReferences,
   };
   return response;
diff --git a/packages/react/src/__tests__/ReactStrictMode-test.internal.js b/packages/react/src/__tests__/ReactStrictMode-test.internal.js
index ed9ee70279648..2867e06483792 100644
--- a/packages/react/src/__tests__/ReactStrictMode-test.internal.js
+++ b/packages/react/src/__tests__/ReactStrictMode-test.internal.js
@@ -179,6 +179,40 @@ describe('ReactStrictMode', () => {
           'B: useEffect mount',
         ]);
       });
+
+      it('should support nested strict mode on initial mount', async () => {
+        function Wrapper({children}) {
+          return children;
+        }
+        await act(() => {
+          const container = document.createElement('div');
+          const root = ReactDOMClient.createRoot(container);
+          root.render(
+            <Wrapper>
+              <Component label="A" />
+              <React.StrictMode>
+                <Component label="B" />,
+              </React.StrictMode>
+              ,
+            </Wrapper>,
+          );
+        });
+
+        expect(log).toEqual([
+          'A: render',
+          'B: render',
+          'B: render',
+          'A: useLayoutEffect mount',
+          'B: useLayoutEffect mount',
+          'A: useEffect mount',
+          'B: useEffect mount',
+          // TODO: this is currently broken
+          // 'B: useLayoutEffect unmount',
+          // 'B: useEffect unmount',
+          // 'B: useLayoutEffect mount',
+          // 'B: useEffect mount',
+        ]);
+      });
     }
   });
 });
diff --git a/packages/scheduler/src/SchedulerFeatureFlags.js b/packages/scheduler/src/SchedulerFeatureFlags.js
index a5166f9813193..6828d0105ebb5 100644
--- a/packages/scheduler/src/SchedulerFeatureFlags.js
+++ b/packages/scheduler/src/SchedulerFeatureFlags.js
@@ -7,7 +7,6 @@
  * @flow strict
  */
 
-export const enableSchedulerDebugging = false;
 export const enableProfiling = false;
 export const frameYieldMs = 5;
 
diff --git a/packages/scheduler/src/forks/Scheduler.js b/packages/scheduler/src/forks/Scheduler.js
index 3fe4d1720fc38..8b34f26bd0551 100644
--- a/packages/scheduler/src/forks/Scheduler.js
+++ b/packages/scheduler/src/forks/Scheduler.js
@@ -12,7 +12,6 @@
 import type {PriorityLevel} from '../SchedulerPriorities';
 
 import {
-  enableSchedulerDebugging,
   enableProfiling,
   frameYieldMs,
   userBlockingPriorityTimeout,
@@ -83,9 +82,6 @@ var timerQueue: Array<Task> = [];
 // Incrementing id counter. Used to maintain insertion order.
 var taskIdCounter = 1;
 
-// Pausing the scheduler is useful for debugging.
-var isSchedulerPaused = false;
-
 var currentTask = null;
 var currentPriorityLevel = NormalPriority;
 
@@ -193,10 +189,7 @@ function workLoop(initialTime: number) {
   let currentTime = initialTime;
   advanceTimers(currentTime);
   currentTask = peek(taskQueue);
-  while (
-    currentTask !== null &&
-    !(enableSchedulerDebugging && isSchedulerPaused)
-  ) {
+  while (currentTask !== null) {
     if (!enableAlwaysYieldScheduler) {
       if (currentTask.expirationTime > currentTime && shouldYieldToHost()) {
         // This currentTask hasn't expired, and we've reached the deadline.
@@ -422,22 +415,6 @@ function unstable_scheduleCallback(
   return newTask;
 }
 
-function unstable_pauseExecution() {
-  isSchedulerPaused = true;
-}
-
-function unstable_continueExecution() {
-  isSchedulerPaused = false;
-  if (!isHostCallbackScheduled && !isPerformingWork) {
-    isHostCallbackScheduled = true;
-    requestHostCallback();
-  }
-}
-
-function unstable_getFirstCallbackNode(): Task | null {
-  return peek(taskQueue);
-}
-
 function unstable_cancelCallback(task: Task) {
   if (enableProfiling) {
     if (task.isQueued) {
@@ -606,9 +583,6 @@ export {
   unstable_getCurrentPriorityLevel,
   shouldYieldToHost as unstable_shouldYield,
   requestPaint as unstable_requestPaint,
-  unstable_continueExecution,
-  unstable_pauseExecution,
-  unstable_getFirstCallbackNode,
   getCurrentTime as unstable_now,
   forceFrameRate as unstable_forceFrameRate,
 };
diff --git a/packages/scheduler/src/forks/SchedulerFeatureFlags.www.js b/packages/scheduler/src/forks/SchedulerFeatureFlags.www.js
index 1d6b955eb8888..2873dee099787 100644
--- a/packages/scheduler/src/forks/SchedulerFeatureFlags.www.js
+++ b/packages/scheduler/src/forks/SchedulerFeatureFlags.www.js
@@ -12,7 +12,6 @@ const dynamicFeatureFlags = require('SchedulerFeatureFlags');
 
 export const {enableRequestPaint} = dynamicFeatureFlags;
 
-export const enableSchedulerDebugging = false;
 export const enableProfiling = __DEV__;
 export const frameYieldMs = 10;
 
diff --git a/packages/scheduler/src/forks/SchedulerMock.js b/packages/scheduler/src/forks/SchedulerMock.js
index 7f148c45be3e4..b638bf1eaf519 100644
--- a/packages/scheduler/src/forks/SchedulerMock.js
+++ b/packages/scheduler/src/forks/SchedulerMock.js
@@ -12,10 +12,7 @@
 
 import type {PriorityLevel} from '../SchedulerPriorities';
 
-import {
-  enableSchedulerDebugging,
-  enableProfiling,
-} from '../SchedulerFeatureFlags';
+import {enableProfiling} from '../SchedulerFeatureFlags';
 import {push, pop, peek} from '../SchedulerMinHeap';
 
 // TODO: Use symbols?
@@ -72,9 +69,6 @@ var timerQueue: Array<Task> = [];
 // Incrementing id counter. Used to maintain insertion order.
 var taskIdCounter = 1;
 
-// Pausing the scheduler is useful for debugging.
-var isSchedulerPaused = false;
-
 var currentTask = null;
 var currentPriorityLevel = NormalPriority;
 
@@ -195,10 +189,7 @@ function workLoop(hasTimeRemaining: boolean, initialTime: number): boolean {
   let currentTime = initialTime;
   advanceTimers(currentTime);
   currentTask = peek(taskQueue);
-  while (
-    currentTask !== null &&
-    !(enableSchedulerDebugging && isSchedulerPaused)
-  ) {
+  while (currentTask !== null) {
     if (
       currentTask.expirationTime > currentTime &&
       (!hasTimeRemaining || shouldYieldToHost())
@@ -422,22 +413,6 @@ function unstable_scheduleCallback(
   return newTask;
 }
 
-function unstable_pauseExecution() {
-  isSchedulerPaused = true;
-}
-
-function unstable_continueExecution() {
-  isSchedulerPaused = false;
-  if (!isHostCallbackScheduled && !isPerformingWork) {
-    isHostCallbackScheduled = true;
-    requestHostCallback(flushWork);
-  }
-}
-
-function unstable_getFirstCallbackNode(): Task | null {
-  return peek(taskQueue);
-}
-
 function unstable_cancelCallback(task: Task) {
   if (enableProfiling) {
     if (task.isQueued) {
@@ -679,9 +654,6 @@ export {
   unstable_getCurrentPriorityLevel,
   shouldYieldToHost as unstable_shouldYield,
   requestPaint as unstable_requestPaint,
-  unstable_continueExecution,
-  unstable_pauseExecution,
-  unstable_getFirstCallbackNode,
   getCurrentTime as unstable_now,
   forceFrameRate as unstable_forceFrameRate,
   unstable_flushAllWithoutAsserting,
diff --git a/packages/scheduler/src/forks/SchedulerNative.js b/packages/scheduler/src/forks/SchedulerNative.js
index 3832cbc69753e..33f9ae3313534 100644
--- a/packages/scheduler/src/forks/SchedulerNative.js
+++ b/packages/scheduler/src/forks/SchedulerNative.js
@@ -97,9 +97,6 @@ export const unstable_now: () => number | DOMHighResTimeStamp =
 export const unstable_next: any = throwNotImplemented;
 export const unstable_runWithPriority: any = throwNotImplemented;
 export const unstable_wrapCallback: any = throwNotImplemented;
-export const unstable_continueExecution: any = throwNotImplemented;
-export const unstable_pauseExecution: any = throwNotImplemented;
-export const unstable_getFirstCallbackNode: any = throwNotImplemented;
 export const unstable_forceFrameRate: any = throwNotImplemented;
 export const unstable_Profiling: any = null;
 
diff --git a/packages/scheduler/src/forks/SchedulerPostTask.js b/packages/scheduler/src/forks/SchedulerPostTask.js
index a029fce0cbfcc..7465c38b92f8a 100644
--- a/packages/scheduler/src/forks/SchedulerPostTask.js
+++ b/packages/scheduler/src/forks/SchedulerPostTask.js
@@ -234,13 +234,5 @@ export function unstable_wrapCallback<T>(callback: () => T): () => T {
 
 export function unstable_forceFrameRate() {}
 
-export function unstable_pauseExecution() {}
-
-export function unstable_continueExecution() {}
-
-export function unstable_getFirstCallbackNode(): null {
-  return null;
-}
-
 // Currently no profiling build
 export const unstable_Profiling = null;
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 8540d6e14721a..7d45abe69f5a9 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -186,12 +186,6 @@ export const disableLegacyContext = true;
  */
 export const disableLegacyContextForFunctionComponents = true;
 
-// Not ready to break experimental yet.
-// Modern <StrictMode /> behaviour aligns more with what components
-// components will encounter in production, especially when used With <Offscreen />.
-// TODO: clean up legacy <StrictMode /> once tests pass WWW.
-export const useModernStrictMode = true;
-
 // Enable the moveBefore() alternative to insertBefore(). This preserves states of moves.
 export const enableMoveBefore = false;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 45807e9d876af..73ccd5fb8eda9 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -80,7 +80,6 @@ export const renameElementSymbol = false;
 export const retryLaneExpirationMs = 5000;
 export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
-export const useModernStrictMode = true;
 export const enableHydrationLaneScheduling = true;
 export const enableYieldingBeforePassive = false;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index c29da18a42055..7699aa73f7fa7 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -70,7 +70,6 @@ export const renameElementSymbol = true;
 export const retryLaneExpirationMs = 5000;
 export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
-export const useModernStrictMode = true;
 export const enableSiblingPrerendering = true;
 export const enableUseResourceEffectHook = false;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index df58c53eda9a4..c23c4ba131a72 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -52,7 +52,6 @@ export const enableLegacyHidden = false;
 
 export const enableTransitionTracing = false;
 
-export const useModernStrictMode = true;
 export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
 export const enableFizzExternalRuntime = true;
 export const enableDeferRootSchedulingToMicrotask = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
index a4dc5cb76d109..8574f34c4e952 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
@@ -65,7 +65,6 @@ export const renameElementSymbol = false;
 export const retryLaneExpirationMs = 5000;
 export const syncLaneExpirationMs = 250;
 export const transitionLaneExpirationMs = 5000;
-export const useModernStrictMode = true;
 export const enableFabricCompleteRootInCommitPhase = false;
 export const enableSiblingPrerendering = true;
 export const enableUseResourceEffectHook = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index e7c92602a0abf..97743f0d46ae9 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -54,7 +54,6 @@ export const enableLegacyHidden = false;
 
 export const enableTransitionTracing = false;
 
-export const useModernStrictMode = true;
 export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
 export const enableFizzExternalRuntime = false;
 export const enableDeferRootSchedulingToMicrotask = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index da62754a13359..c027e2bdc121c 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -106,7 +106,6 @@ export const disableClientCache = true;
 export const enableServerComponentLogs = true;
 
 export const enableReactTestRendererWarning = false;
-export const useModernStrictMode = true;
 
 export const disableLegacyMode = true;
 
diff --git a/scripts/jest/setupTests.www.js b/scripts/jest/setupTests.www.js
index efee213861ca6..b0b653bb78ff9 100644
--- a/scripts/jest/setupTests.www.js
+++ b/scripts/jest/setupTests.www.js
@@ -34,9 +34,9 @@ jest.mock('scheduler/src/SchedulerFeatureFlags', () => {
     schedulerSrcPath + '/src/forks/SchedulerFeatureFlags.www'
   );
 
-  // These flags are not a dynamic on www, but we still want to run
-  // tests in both versions.
-  actual.enableSchedulerDebugging = __VARIANT__;
+  // Add flags here that are not a dynamic on www,
+  // but we still want to run tests in both versions.
+  // <this list is empty>
 
   return actual;
 });