Two of my guesses why would I be banned are:
1. I didn't have any activity on itch for more then a year and then I suddenly decided to post a game and make a few comments.
2. I'm russian, and also have to use vpn because itch is blocked here for god know reason.
Hmm, your first idea seems like a strong possibility too. I also stopped using itch.io for a long time before coming back and starting to use it again. That's when my comments on the main pages of games started getting stuck waiting for mod approval that never comes. It doesn't help that I messaged Support over a month ago, and it's been complete radio silence from them after the initial bot reply stating that they got my ticket.