I think it’s either a bug or related to server load. I made a post on this community noting the same thing. It’s like instances are not communicating with each other right now.
I looked at the same post from 4 different instances and got four different results in both comment count and votes.
From the server it was originally posted on (currently at 9 comments): https://lemmy.ml/post/1244889
lemmy.world (8 comments): https://lemmy.world/post/112477
beehaw.org (10 comments): https://beehaw.org/post/542091
sh.itjust.works (5 comments): https://sh.itjust.works/post/79680