Just seen this on the Arqade Review page:
Do we really have 1.7k late answers to review? I skipped through a couple and the answers do seem to be queued.
Is that a bug? Or what is it?
No, it's not a bug. Upon accessing the review queue, answers dating all the way back to a few years ago can be seen, as the reputation thresholds for Late Answers have been changed. Answers are now eligible to go into the queue if the person answering has any less than 50 reputation earned on the site rather than just 1 reputation.
may well have been is definitely something caused by this Meta.SE suggestion being put into place.
Another meta post also shows that this isn't exclusive to Arqade, and is in fact widespread across each SE site.