diff --git a/packages/react-reconciler/src/__tests__/ReactLazy-test.internal.js b/packages/react-reconciler/src/__tests__/ReactLazy-test.internal.js
index b7f1570823c14..b9e6b0c268061 100644
--- a/packages/react-reconciler/src/__tests__/ReactLazy-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactLazy-test.internal.js
@@ -1271,6 +1271,9 @@ describe('ReactLazy', () => {
   // @gate enableLazyElements
   it('mount and reorder lazy types', async () => {
     class Child extends React.Component {
+      componentWillUnmount() {
+        Scheduler.unstable_yieldValue('Did unmount: ' + this.props.label);
+      }
       componentDidMount() {
         Scheduler.unstable_yieldValue('Did mount: ' + this.props.label);
       }
@@ -1348,6 +1351,12 @@ describe('ReactLazy', () => {
     expect(Scheduler).toFlushAndYield(['Init B2', 'Loading...']);
     jest.runAllTimers();
 
+    gate(flags => {
+      if (flags.enableSuspenseLayoutEffectSemantics) {
+        expect(Scheduler).toHaveYielded(['Did unmount: A', 'Did unmount: B']);
+      }
+    });
+
     // The suspense boundary should've triggered now.
     expect(root).toMatchRenderedOutput('Loading...');
     await resolveB2({default: ChildB});
@@ -1356,12 +1365,23 @@ describe('ReactLazy', () => {
     expect(Scheduler).toFlushAndYield(['Init A2']);
     await LazyChildA2;
 
-    expect(Scheduler).toFlushAndYield([
-      'b',
-      'a',
-      'Did update: b',
-      'Did update: a',
-    ]);
+    gate(flags => {
+      if (flags.enableSuspenseLayoutEffectSemantics) {
+        expect(Scheduler).toFlushAndYield([
+          'b',
+          'a',
+          'Did mount: b',
+          'Did mount: a',
+        ]);
+      } else {
+        expect(Scheduler).toFlushAndYield([
+          'b',
+          'a',
+          'Did update: b',
+          'Did update: a',
+        ]);
+      }
+    });
     expect(root).toMatchRenderedOutput('ba');
   });
 
diff --git a/packages/react-reconciler/src/__tests__/ReactSuspenseFuzz-test.internal.js b/packages/react-reconciler/src/__tests__/ReactSuspenseFuzz-test.internal.js
index c67edf8a15632..a0a0d08a2c42b 100644
--- a/packages/react-reconciler/src/__tests__/ReactSuspenseFuzz-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactSuspenseFuzz-test.internal.js
@@ -100,7 +100,7 @@ describe('ReactSuspenseFuzz', () => {
         }
       }, [updates]);
 
-      const fullText = `${text}:${step}`;
+      const fullText = `[${text}:${step}]`;
 
       const shouldSuspend = useContext(ShouldSuspendContext);
 
@@ -163,19 +163,26 @@ describe('ReactSuspenseFuzz', () => {
       resolveAllTasks();
       const expectedOutput = expectedRoot.getChildrenAsJSX();
 
-      resetCache();
-      ReactNoop.renderLegacySyncRoot(children);
-      resolveAllTasks();
-      const legacyOutput = ReactNoop.getChildrenAsJSX();
-      expect(legacyOutput).toEqual(expectedOutput);
-      ReactNoop.renderLegacySyncRoot(null);
-
-      resetCache();
-      const concurrentRoot = ReactNoop.createRoot();
-      concurrentRoot.render(children);
-      resolveAllTasks();
-      const concurrentOutput = concurrentRoot.getChildrenAsJSX();
-      expect(concurrentOutput).toEqual(expectedOutput);
+      gate(flags => {
+        resetCache();
+        ReactNoop.renderLegacySyncRoot(children);
+        resolveAllTasks();
+        const legacyOutput = ReactNoop.getChildrenAsJSX();
+        expect(legacyOutput).toEqual(expectedOutput);
+        ReactNoop.renderLegacySyncRoot(null);
+
+        // Observable behavior differs here in a way that's expected:
+        // If enableSuspenseLayoutEffectSemantics is enabled, layout effects are destroyed on re-suspend
+        // before larger 'beginAfter' timers have a chance to fire.
+        if (!flags.enableSuspenseLayoutEffectSemantics) {
+          resetCache();
+          const concurrentRoot = ReactNoop.createRoot();
+          concurrentRoot.render(children);
+          resolveAllTasks();
+          const concurrentOutput = concurrentRoot.getChildrenAsJSX();
+          expect(concurrentOutput).toEqual(expectedOutput);
+        }
+      });
     }
 
     function pickRandomWeighted(rand, options) {
@@ -410,5 +417,32 @@ Random seed is ${SEED}
         </>,
       );
     });
+
+    it('4', () => {
+      const {Text, testResolvedOutput} = createFuzzer();
+      testResolvedOutput(
+        <React.Suspense fallback="Loading...">
+          <React.Suspense>
+            <React.Suspense>
+              <Text initialDelay={9683} text="E" updates={[]} />
+            </React.Suspense>
+            <Text
+              initialDelay={4053}
+              text="C"
+              updates={[
+                {
+                  beginAfter: 1566,
+                  suspendFor: 4142,
+                },
+                {
+                  beginAfter: 9572,
+                  suspendFor: 4832,
+                },
+              ]}
+            />
+          </React.Suspense>
+        </React.Suspense>,
+      );
+    });
   });
 });
diff --git a/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js b/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
index 692b745f97085..9d6056e25d3db 100644
--- a/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
@@ -468,19 +468,30 @@ describe('ReactSuspenseWithNoopRenderer', () => {
 
     await rejectText('Result', new Error('Failed to load: Result'));
 
-    expect(Scheduler).toFlushAndYield([
-      'Error! [Result]',
+    gate(flags => {
+      if (flags.enableSuspenseLayoutEffectSemantics) {
+        expect(Scheduler).toFlushAndYield([
+          'Error! [Result]',
 
-      // React retries one more time
-      'Error! [Result]',
+          // React retries one more time
+          'Error! [Result]',
+        ]);
+        expect(ReactNoop.getChildren()).toEqual([]);
+      } else {
+        expect(Scheduler).toFlushAndYield([
+          'Error! [Result]',
 
-      // Errored again on retry. Now handle it.
+          // React retries one more time
+          'Error! [Result]',
 
-      'Caught error: Failed to load: Result',
-    ]);
-    expect(ReactNoop.getChildren()).toEqual([
-      span('Caught error: Failed to load: Result'),
-    ]);
+          // Errored again on retry. Now handle it.
+          'Caught error: Failed to load: Result',
+        ]);
+        expect(ReactNoop.getChildren()).toEqual([
+          span('Caught error: Failed to load: Result'),
+        ]);
+      }
+    });
   });
 
   // @gate enableCache