[Strange thing happened] Blocked person that unblocked himself?!

Hello, I blocked someone on IG 2 days ago.
Today I found out that the same person is back seeing my posts and is back able to like and comment stupid things.

I checked, and this person was unblocked, so I blocked once again.

Does anybody know how it is possible that this person somehow unblocked himself? There is for sure some trick to get unblocked after being blocked by somebody.

he prolly made a new account

No, same account, same photos, same likes, same comments I left to old pictures weeks/months ago, same nick, etc.

I am wondering whether changed the nick for a moment and them changed it back to the old one. It may be the trick, but untested. Maybe if the blocks are to the username and to the the userID changing the nick resets all the blocks.

do you use a follow liker bot or something like that? if you block somebody and the bot follows that person again it might happen that the person gets unblocked.

No bot. But it may have happened that I followed that person manually by mistake. So probably that's the reason