I’ve found that some “rejected users” users seem to clog up the queue. Although the default filter for the Review Queue hides them, they can be found if the filtering is cleared. Unfortunately, as a Moderator, I cannot filter for “rejected” or “No” status approvals. And even if I can find those rejected and not approved people in the Queue, I cannot access them in the User lists. They are masked there somehow. So there is no way to delete the users as a moderator.
So it always looks like there are users waiting.
