docs(mutations): Update mutations page side effects section (TanStack#2354)

Author: rob-jed

docs/src/pages/guides/mutations.md

@@ -149,7 +149,7 @@ useMutation(addTodo, {
 })
 ```
 
-You might find that you want to **trigger additional callbacks** than the ones defined on `useMutation` when calling `mutate`. This can be used to trigger component-specific side effects. To do that, you can provide any of the same callback options to the `mutate` function after your mutation variable. Supported overrides include: `onSuccess`, `onError` and `onSettled`.
+You might find that you want to **trigger additional callbacks** than the ones defined on `useMutation` when calling `mutate`. This can be used to trigger component-specific side effects. To do that, you can provide any of the same callback options to the `mutate` function after your mutation variable. Supported overrides include: `onSuccess`, `onError` and `onSettled`. Please keep in mind that those additional callbacks won't run if your component unmounts _before_ the mutation finishes.
 
 ```js
 useMutation(addTodo, {