Is your proton set to experimental? because mine is working on arch. If it is, try verifying files, or if that doesn't work, back up your saves and nuke the prefix.

Fromsoft is just checking up on you. Have you been acting differently since the dlc came out?

I caught a ban as soon as the DLC launched. Dont even have any mods installed. Had to appeal.

To add to what everyone else said, it's a known issue. Easy Anti-Cheat isn't working properly on Linux unless you own the DLC. It's working fine on my end since I own it.

Didn't even buy the DLC.

That's the issue, game works fine with the DLC and fails without the DLC.

At least when playing offline you can use er-patcher to play it without framerate limit, chromatic aberration and in ultrawide. https://github.com/gurrgur/er-patcher

This was patched in experimental 2 days ago. I downloaded update as soon as it was live and I have almost finished the DLC.