You saw this problem on PG16? Did you see vacuum hanging or you saw some kind of incorrect relfrozenxid advancement? My repro does not work for PG16, and I do not see how we could face this problem on PG16. It would be very helpful if you have any more details.
Yes, I found the vacuum process hanging in a retry loop on PG16. I think it was the problem discussed in this thread. Here is some information: