Sandbox: https://codesandbox.io/s/cranky-kapitsa-op3jh

Repro: type "a" and then after a second "b"

Expected: Eventually you'll see "ab" in all fields. Pending "..." indicator goes away.

Actual: You'll keep seeing "a" in low pri field. Pending "..." indicator is stuck.
React.useEffect(() => {
            Scheduler.unstable_yieldValue('b:passive create');
            return () => {
              Scheduler.unstable_yieldValue('b:passive destroy');
            };
          }, []);
          return null;
        }
        act(() => {
          ReactNoop.renderToRootWithID(
            <>
              <ComponentWithXHR />
              <ComponentWithPendingPassiveUnmount />
            </>,
            'root',