diff --git a/packages/react-reconciler/src/__tests__/ReactExpiration-test.js b/packages/react-reconciler/src/__tests__/ReactExpiration-test.js
index 72ca257fef..beaa511f5a 100644
--- a/packages/react-reconciler/src/__tests__/ReactExpiration-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactExpiration-test.js
@@ -508,13 +508,9 @@ describe('ReactExpiration', () => {
 
     // First demonstrate what happens when there's no starvation
     await act(async () => {
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          updateNormalPri();
-        });
-      } else {
+      React.startTransition(() => {
         updateNormalPri();
-      }
+      });
       expect(Scheduler).toFlushAndYieldThrough(['Sync pri: 0']);
       updateSyncPri();
       expect(Scheduler).toHaveYielded(['Sync pri: 1', 'Normal pri: 0']);
@@ -532,13 +528,9 @@ describe('ReactExpiration', () => {
 
     // Do the same thing, but starve the first update
     await act(async () => {
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          updateNormalPri();
-        });
-      } else {
+      React.startTransition(() => {
         updateNormalPri();
-      }
+      });
       expect(Scheduler).toFlushAndYieldThrough(['Sync pri: 1']);
 
       // This time, a lot of time has elapsed since the normal pri update
diff --git a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
index ac6f312e5d..8e689ce38f 100644
--- a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
@@ -171,15 +171,10 @@ describe('ReactHooksWithNoopRenderer', () => {
 
     // Schedule some updates
     act(() => {
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          counter.current.updateCount(1);
-          counter.current.updateCount(count => count + 10);
-        });
-      } else {
+      React.startTransition(() => {
         counter.current.updateCount(1);
         counter.current.updateCount(count => count + 10);
-      }
+      });
 
       // Partially flush without committing
       expect(Scheduler).toFlushAndYieldThrough(['Count: 11']);
@@ -815,13 +810,9 @@ describe('ReactHooksWithNoopRenderer', () => {
         ReactNoop.discreteUpdates(() => {
           setRow(5);
         });
-        if (gate(flags => flags.enableSyncDefaultUpdates)) {
-          React.startTransition(() => {
-            setRow(20);
-          });
-        } else {
+        React.startTransition(() => {
           setRow(20);
-        }
+        });
       });
       expect(Scheduler).toHaveYielded(['Up', 'Down']);
       expect(root).toMatchRenderedOutput(<span prop="Down" />);
diff --git a/packages/react-reconciler/src/__tests__/ReactIncremental-test.js b/packages/react-reconciler/src/__tests__/ReactIncremental-test.js
index 8b6226888b..0316744dde 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncremental-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncremental-test.js
@@ -215,17 +215,7 @@ describe('ReactIncremental', () => {
     ReactNoop.render(<Foo />);
     expect(Scheduler).toFlushWithoutYielding();
 
-    if (gate(flags => flags.enableSyncDefaultUpdates)) {
-      React.startTransition(() => {
-        inst.setState(
-          () => {
-            Scheduler.unstable_yieldValue('setState1');
-            return {text: 'bar'};
-          },
-          () => Scheduler.unstable_yieldValue('callback1'),
-        );
-      });
-    } else {
+    React.startTransition(() => {
       inst.setState(
         () => {
           Scheduler.unstable_yieldValue('setState1');
@@ -233,24 +223,14 @@ describe('ReactIncremental', () => {
         },
         () => Scheduler.unstable_yieldValue('callback1'),
       );
-    }
+    });
 
     // Flush part of the work
     expect(Scheduler).toFlushAndYieldThrough(['setState1']);
 
     // This will abort the previous work and restart
     ReactNoop.flushSync(() => ReactNoop.render(<Foo />));
-    if (gate(flags => flags.enableSyncDefaultUpdates)) {
-      React.startTransition(() => {
-        inst.setState(
-          () => {
-            Scheduler.unstable_yieldValue('setState2');
-            return {text2: 'baz'};
-          },
-          () => Scheduler.unstable_yieldValue('callback2'),
-        );
-      });
-    } else {
+    React.startTransition(() => {
       inst.setState(
         () => {
           Scheduler.unstable_yieldValue('setState2');
@@ -258,7 +238,7 @@ describe('ReactIncremental', () => {
         },
         () => Scheduler.unstable_yieldValue('callback2'),
       );
-    }
+    });
 
     // Flush the rest of the work which now includes the low priority
     expect(Scheduler).toFlushAndYield([
diff --git a/packages/react-reconciler/src/__tests__/ReactSuspenseList-test.js b/packages/react-reconciler/src/__tests__/ReactSuspenseList-test.js
index b7cdc19d63..cbfb8f8996 100644
--- a/packages/react-reconciler/src/__tests__/ReactSuspenseList-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactSuspenseList-test.js
@@ -2549,13 +2549,9 @@ describe('ReactSuspenseList', () => {
 
     await act(async () => {
       // Add a few items at the end.
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          updateLowPri(true);
-        });
-      } else {
+      React.startTransition(() => {
         updateLowPri(true);
-      }
+      });
 
       // Flush partially through.
       expect(Scheduler).toFlushAndYieldThrough(['B', 'C']);
diff --git a/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js b/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
index 9d95a57572..8652e3c3db 100644
--- a/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
@@ -3796,7 +3796,6 @@ describe('ReactSuspenseWithNoopRenderer', () => {
   });
 
   // @gate enableLegacyCache
-  // @gate !enableSyncDefaultUpdates
   it('regression: ping at high priority causes update to be dropped', async () => {
     const {useState, useTransition} = React;
 
@@ -3863,10 +3862,9 @@ describe('ReactSuspenseWithNoopRenderer', () => {
       });
 
       expect(Scheduler).toFlushAndYield([
-        'B',
         'Suspend! [A1]',
         'Loading...',
-
+        'B',
         'Suspend! [A2]',
         'Loading...',
         'Suspend! [B2]',
@@ -3882,6 +3880,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
       await resolveText('A1');
       expect(Scheduler).toFlushAndYield([
         'A1',
+        'B',
         'Suspend! [A2]',
         'Loading...',
         'Suspend! [B2]',
diff --git a/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js b/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
index ef452cc581..a1d5912ebc 100644
--- a/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
@@ -454,13 +454,9 @@ describe('useMutableSource', () => {
 
       // Changing values should schedule an update with React.
       // Start working on this update but don't finish it.
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          source.value = 'two';
-        });
-      } else {
+      React.startTransition(() => {
         source.value = 'two';
-      }
+      });
       expect(Scheduler).toFlushAndYieldThrough(['a:two']);
 
       // Re-renders that occur before the update is processed
diff --git a/packages/react/src/__tests__/ReactProfiler-test.internal.js b/packages/react/src/__tests__/ReactProfiler-test.internal.js
index 3d7e061851..197aa4100c 100644
--- a/packages/react/src/__tests__/ReactProfiler-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfiler-test.internal.js
@@ -1065,13 +1065,9 @@ describe(`onRender`, () => {
 
       // Render a partially update, but don't finish.
       // This partial render will take 10ms of actual render time.
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          first.setState({renderTime: 10});
-        });
-      } else {
+      React.startTransition(() => {
         first.setState({renderTime: 10});
-      }
+      });
       expect(Scheduler).toFlushAndYieldThrough(['FirstComponent:10']);
       expect(callback).toHaveBeenCalledTimes(0);
 
diff --git a/packages/use-subscription/src/__tests__/useSubscription-test.js b/packages/use-subscription/src/__tests__/useSubscription-test.js
index 4ce88b8134..89ec3327c7 100644
--- a/packages/use-subscription/src/__tests__/useSubscription-test.js
+++ b/packages/use-subscription/src/__tests__/useSubscription-test.js
@@ -439,13 +439,9 @@ describe('useSubscription', () => {
 
     // Start React update, but don't finish
     act(() => {
-      if (gate(flags => flags.enableSyncDefaultUpdates)) {
-        React.startTransition(() => {
-          renderer.update(<Parent observed={observableB} />);
-        });
-      } else {
+      React.startTransition(() => {
         renderer.update(<Parent observed={observableB} />);
-      }
+      });
       expect(Scheduler).toFlushAndYieldThrough(['Child: b-0']);
       expect(log).toEqual([]);