I have found the red alert has been helpful in prompting me to review queues.
There should be red when there's red dots against review queues:
image stolen from When I look at the review icon, I see red
However, when I have used all my reviews for some queues:
If those queues are large enough to warrant the red alert, it will still show on my review icon, even though none of the queues I am able to review in are not alerting.
It would be better if it is like this:
Can we have the red alert vanish if the alert is for queues we have finished reviewing for the day please? It's honestly annoying and will eventually degrade the UX for avid reviewers. (imo)