If you're able to, you could try to connect to another server using your VPN. Otherwise, you may be able to contact one of the mods through the Discord channel.
Honestly, I am not sure whether this is the right place to ask this question. I'm only here because I noticed your post and had a sudden, similar issue. I've got a feeling that it is a technical problem, as I am pretty sure that I did nothing against the rules in my case and the problem only occurred as I tried to log on the other day. Would seem odd to me to ban people while they're offline without any warning or details as of why they're banned. I noticed that the anticheat system was updated some days ago, so maybe it has to do with that?
Anyways, if you don't get any response or workable solution on here, I think your best bet is directly contacting a mod or admin. I'm probably going to do so as well, as I don't always want to rely on my VPN connection to play the game.
EDIT: Just posted a message on the Discord channel and it seems that more people are experiencing this problem. From what I was told, the mods are already aware of the problem and currently looking further into it. I guess the best you can do is let them know you were affected too and wait it out.