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.
);
        expect(Scheduler).toFlushAndYieldThrough(['Count: 1', 'Sync effect']);
        expect(ReactNoop.getChildren()).toEqual([span('Count: 1')]);
      });
      expect(Scheduler).toHaveYielded([
        'Unmount A [0]',
        'Unmount B [0]',
        'Mount A [1]',
        'Mount B [1]',
      ]);
    });
    if (runAllPassiveEffectDestroysBeforeCreates) {
      it('unmounts all previous effects between siblings before creating any new ones', () => {
        function Counter({count, label}) {
          useEffect(() => {
            Scheduler.unstable_yieldValue(`Mount ${label} [${count}]`);
            return () => {
              Scheduler.unstable_yieldValue(`Unmount ${label} [${count}]`);
            };
          });
          return <Text text={`${label} ${count}`} />;
        }
        act(() => {
          ReactNoop.render(
            <>
              <Counter label="A" count={0} />
              <Counter label="B" count={0} />
            </>,
            () => Scheduler.unstable_yieldValue('Sync effect'),
          );