I'm seeing the red alert on sites where there's nothing to review:
That's from Community Building, where I'm pretty sure the queues are empty. I also just saw it on Worldbuilding meta, where I'm a moderator and also see nothing special (like pending VLQ/NAA flags).
And it's sticking around after I close the dialogue. Visiting one of the review queues from the drop-down didn't dismiss it either.