packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js

@@ -1838,10 +1838,6 @@ describe('ReactIncrementalErrorHandling', () => {
           "If you can't use a class try assigning the prototype on the function as a workaround. " +
           '`Provider.prototype = React.Component.prototype`. ' +
           "Don't use an arrow function since it cannot be called with `new` by React.",
-        'Legacy context API has been detected within a strict-mode tree.\n\n' +
-          'The old API will be supported in all 16.x releases, but ' +
-          'applications using it should migrate to the new version.\n\n' +
-          'Please update the following components: Provider',
       ]);
     });
   }

packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js

@@ -1815,6 +1815,7 @@ describe('useMutableSource', () => {
   if (__DEV__) {
     // See https://github.com/facebook/react/issues/19948
     describe('side effecte detection', () => {
+      // @gate experimental
       it('should throw if a mutable source is mutated during render', () => {
         const source = createSource(0);
         const mutableSource = createMutableSource(