Occasionally I see a red dot on the Review Queue button (top right). While it seems to work as normal, and doesn't look like there are no more questions / answers than normal to review, I wondered about its meaning? Does it imply review items that have been waiting a while?
From this answer by a former staff member:
the idea is that when you see the indicator light up, it’s a reminder that there are reviews to be done if you haven’t looked recently. The goal is to draw reviewers’ attention to queues that can use some help.
It also contains details about the implementation specifics.