I'm banned but I've never even joined this server?
This can occur for a multitude of reasons, but is quite a rare event on our Network.
The most common reason players encounter this issue is due to players joining our network and cheating while using Cloud Gaming Services, such as GeForceNow, Google Stadia and much more. When this occurs and a player is banned, we ban their IP address associated with the Steam account, which is actually the IP address of the Cloud Gaming Service, not the clients home IP address. This is where the issue begins. Legitimate players (possibly you) try to connect with that same exact IP address associated with your Cloud Instance, and boom we ban you automatically because we assume you're the previous cheater who was banned, judging by your IP address. We've even seen this scale to very high numbers, topping at 50 false banned steam accounts all from just 1 user who cheated on the Cloud Gaming Service. In the future we may create automated systems to counter this problem, but for now it isn't quite yet big enough of an issue.
We've been noticing Cloud Gaming is getting much bigger, therefor we're running into the issue more and more each year. If you've suffered from this issue, feel free to create a support ticket here and you'll receive a response from us shortly.