diff --git a/packages/react-dom/src/events/ReactDOMEventListener.js b/packages/react-dom/src/events/ReactDOMEventListener.js
index 81b3a1b85dce4..590d8c2d9f5b3 100644
--- a/packages/react-dom/src/events/ReactDOMEventListener.js
+++ b/packages/react-dom/src/events/ReactDOMEventListener.js
@@ -49,9 +49,6 @@ import {
   getCurrentUpdatePriority,
   setCurrentUpdatePriority,
 } from 'react-reconciler/src/ReactEventPriorities';
-import ReactSharedInternals from 'shared/ReactSharedInternals';
-
-const {ReactCurrentBatchConfig} = ReactSharedInternals;
 
 // TODO: can we stop exporting these?
 export let _enabled = true;
@@ -128,14 +125,11 @@ function dispatchContinuousEvent(
   nativeEvent,
 ) {
   const previousPriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
-  ReactCurrentBatchConfig.transition = 0;
   try {
     setCurrentUpdatePriority(ContinuousEventPriority);
     dispatchEvent(domEventName, eventSystemFlags, container, nativeEvent);
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
   }
 }
 
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
index 0b15fb13a2351..99f3e014148f5 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
@@ -245,7 +245,6 @@ const ceil = Math.ceil;
 const {
   ReactCurrentDispatcher,
   ReactCurrentOwner,
-  ReactCurrentBatchConfig,
   IsSomeRendererActing,
 } = ReactSharedInternals;
 
@@ -1063,14 +1062,11 @@ export function flushDiscreteUpdates() {
 
 export function deferredUpdates<A>(fn: () => A): A {
   const previousPriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DefaultEventPriority);
     return fn();
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
   }
 }
 
@@ -1114,14 +1110,11 @@ export function discreteUpdates<A, B, C, D, R>(
   d: D,
 ): R {
   const previousPriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     return fn(a, b, c, d);
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
     if (executionContext === NoContext) {
       resetRenderTimer();
     }
@@ -1151,10 +1144,8 @@ export function flushSync<A, R>(fn: A => R, a: A): R {
   const prevExecutionContext = executionContext;
   executionContext |= BatchedContext;
 
-  const prevTransition = ReactCurrentBatchConfig.transition;
   const previousPriority = getCurrentUpdatePriority();
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     if (fn) {
       return fn(a);
@@ -1163,7 +1154,6 @@ export function flushSync<A, R>(fn: A => R, a: A): R {
     }
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
     executionContext = prevExecutionContext;
     // Flush the immediate callbacks that were scheduled during this batch.
     // Note that this will happen even if batchedUpdates is higher up
@@ -1185,15 +1175,12 @@ export function flushSync<A, R>(fn: A => R, a: A): R {
 export function flushControlled(fn: () => mixed): void {
   const prevExecutionContext = executionContext;
   executionContext |= BatchedContext;
-  const prevTransition = ReactCurrentBatchConfig.transition;
   const previousPriority = getCurrentUpdatePriority();
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     fn();
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
 
     executionContext = prevExecutionContext;
     if (executionContext === NoContext) {
@@ -1688,13 +1675,10 @@ function commitRoot(root) {
   // TODO: This no longer makes any sense. We already wrap the mutation and
   // layout phases. Should be able to remove.
   const previousUpdateLanePriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     commitRootImpl(root, previousUpdateLanePriority);
   } finally {
-    ReactCurrentBatchConfig.transition = prevTransition;
     setCurrentUpdatePriority(previousUpdateLanePriority);
   }
 
@@ -1816,8 +1800,6 @@ function commitRootImpl(root, renderPriorityLevel) {
     NoFlags;
 
   if (subtreeHasEffects || rootHasEffect) {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = 0;
     const previousPriority = getCurrentUpdatePriority();
     setCurrentUpdatePriority(DiscreteEventPriority);
 
@@ -1899,7 +1881,6 @@ function commitRootImpl(root, renderPriorityLevel) {
 
     // Reset the priority to the previous non-sync value.
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
   } else {
     // No effects.
     root.current = finishedWork;
@@ -2036,15 +2017,12 @@ export function flushPassiveEffects(): boolean {
   if (rootWithPendingPassiveEffects !== null) {
     const renderPriority = lanesToEventPriority(pendingPassiveEffectsLanes);
     const priority = lowerEventPriority(DefaultEventPriority, renderPriority);
-    const prevTransition = ReactCurrentBatchConfig.transition;
     const previousPriority = getCurrentUpdatePriority();
     try {
-      ReactCurrentBatchConfig.transition = 0;
       setCurrentUpdatePriority(priority);
       return flushPassiveEffectsImpl();
     } finally {
       setCurrentUpdatePriority(previousPriority);
-      ReactCurrentBatchConfig.transition = prevTransition;
     }
   }
   return false;
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
index 7b03e4cc743df..e7328b989083b 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
@@ -245,7 +245,6 @@ const ceil = Math.ceil;
 const {
   ReactCurrentDispatcher,
   ReactCurrentOwner,
-  ReactCurrentBatchConfig,
   IsSomeRendererActing,
 } = ReactSharedInternals;
 
@@ -1063,14 +1062,11 @@ export function flushDiscreteUpdates() {
 
 export function deferredUpdates<A>(fn: () => A): A {
   const previousPriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DefaultEventPriority);
     return fn();
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
   }
 }
 
@@ -1114,14 +1110,11 @@ export function discreteUpdates<A, B, C, D, R>(
   d: D,
 ): R {
   const previousPriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     return fn(a, b, c, d);
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
     if (executionContext === NoContext) {
       resetRenderTimer();
     }
@@ -1151,10 +1144,8 @@ export function flushSync<A, R>(fn: A => R, a: A): R {
   const prevExecutionContext = executionContext;
   executionContext |= BatchedContext;
 
-  const prevTransition = ReactCurrentBatchConfig.transition;
   const previousPriority = getCurrentUpdatePriority();
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     if (fn) {
       return fn(a);
@@ -1163,7 +1154,6 @@ export function flushSync<A, R>(fn: A => R, a: A): R {
     }
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
     executionContext = prevExecutionContext;
     // Flush the immediate callbacks that were scheduled during this batch.
     // Note that this will happen even if batchedUpdates is higher up
@@ -1185,15 +1175,12 @@ export function flushSync<A, R>(fn: A => R, a: A): R {
 export function flushControlled(fn: () => mixed): void {
   const prevExecutionContext = executionContext;
   executionContext |= BatchedContext;
-  const prevTransition = ReactCurrentBatchConfig.transition;
   const previousPriority = getCurrentUpdatePriority();
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     fn();
   } finally {
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
 
     executionContext = prevExecutionContext;
     if (executionContext === NoContext) {
@@ -1688,13 +1675,10 @@ function commitRoot(root) {
   // TODO: This no longer makes any sense. We already wrap the mutation and
   // layout phases. Should be able to remove.
   const previousUpdateLanePriority = getCurrentUpdatePriority();
-  const prevTransition = ReactCurrentBatchConfig.transition;
   try {
-    ReactCurrentBatchConfig.transition = 0;
     setCurrentUpdatePriority(DiscreteEventPriority);
     commitRootImpl(root, previousUpdateLanePriority);
   } finally {
-    ReactCurrentBatchConfig.transition = prevTransition;
     setCurrentUpdatePriority(previousUpdateLanePriority);
   }
 
@@ -1816,8 +1800,6 @@ function commitRootImpl(root, renderPriorityLevel) {
     NoFlags;
 
   if (subtreeHasEffects || rootHasEffect) {
-    const prevTransition = ReactCurrentBatchConfig.transition;
-    ReactCurrentBatchConfig.transition = 0;
     const previousPriority = getCurrentUpdatePriority();
     setCurrentUpdatePriority(DiscreteEventPriority);
 
@@ -1899,7 +1881,6 @@ function commitRootImpl(root, renderPriorityLevel) {
 
     // Reset the priority to the previous non-sync value.
     setCurrentUpdatePriority(previousPriority);
-    ReactCurrentBatchConfig.transition = prevTransition;
   } else {
     // No effects.
     root.current = finishedWork;
@@ -2036,15 +2017,12 @@ export function flushPassiveEffects(): boolean {
   if (rootWithPendingPassiveEffects !== null) {
     const renderPriority = lanesToEventPriority(pendingPassiveEffectsLanes);
     const priority = lowerEventPriority(DefaultEventPriority, renderPriority);
-    const prevTransition = ReactCurrentBatchConfig.transition;
     const previousPriority = getCurrentUpdatePriority();
     try {
-      ReactCurrentBatchConfig.transition = 0;
       setCurrentUpdatePriority(priority);
       return flushPassiveEffectsImpl();
     } finally {
       setCurrentUpdatePriority(previousPriority);
-      ReactCurrentBatchConfig.transition = prevTransition;
     }
   }
   return false;
diff --git a/packages/react-reconciler/src/__tests__/ReactFlushSync-test.js b/packages/react-reconciler/src/__tests__/ReactFlushSync-test.js
index a3df1effd7b35..327b4a87ca678 100644
--- a/packages/react-reconciler/src/__tests__/ReactFlushSync-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactFlushSync-test.js
@@ -3,7 +3,6 @@ let ReactNoop;
 let Scheduler;
 let useState;
 let useEffect;
-let startTransition;
 
 describe('ReactFlushSync', () => {
   beforeEach(() => {
@@ -14,7 +13,6 @@ describe('ReactFlushSync', () => {
     Scheduler = require('scheduler');
     useState = React.useState;
     useEffect = React.useEffect;
-    startTransition = React.unstable_startTransition;
   });
 
   function Text({text}) {
@@ -64,47 +62,6 @@ describe('ReactFlushSync', () => {
     expect(root).toMatchRenderedOutput('1, 1');
   });
 
-  // @gate experimental
-  test('nested with startTransition', async () => {
-    let setSyncState;
-    let setState;
-    function App() {
-      const [syncState, _setSyncState] = useState(0);
-      const [state, _setState] = useState(0);
-      setSyncState = _setSyncState;
-      setState = _setState;
-      return <Text text={`${syncState}, ${state}`} />;
-    }
-
-    const root = ReactNoop.createRoot();
-    await ReactNoop.act(async () => {
-      root.render(<App />);
-    });
-    expect(Scheduler).toHaveYielded(['0, 0']);
-    expect(root).toMatchRenderedOutput('0, 0');
-
-    await ReactNoop.act(async () => {
-      ReactNoop.flushSync(() => {
-        startTransition(() => {
-          // This should be async even though flushSync is on the stack, because
-          // startTransition is closer.
-          setState(1);
-          ReactNoop.flushSync(() => {
-            // This should be async even though startTransition is on the stack,
-            // because flushSync is closer.
-            setSyncState(1);
-          });
-        });
-      });
-      // Only the sync update should have flushed
-      expect(Scheduler).toHaveYielded(['1, 0']);
-      expect(root).toMatchRenderedOutput('1, 0');
-    });
-    // Now the async update has flushed, too.
-    expect(Scheduler).toHaveYielded(['1, 1']);
-    expect(root).toMatchRenderedOutput('1, 1');
-  });
-
   test('flushes passive effects synchronously when they are the result of a sync render', async () => {
     function App() {
       useEffect(() => {