I am using chrome at it also lead me to page 22 instead of page 21 when I click the link on you post history
I am not entirely sure but it is possible that multiple posts were deleted before your post and you post was moved to page 21 from page 22 when the posts were deleted. it happened to me before but I just ignored it and I am not sure what happened but when I checked it again after a couple of days later it was fine.
This is plausible. Though I still think this only happens in the bounty section.
I'm actually using firefox for BTT. I don't know if the problem will get solve by using TOR. Since it's the problem with the link, I think there's a bug in the website code itself.