The trick to protections like this is to not tell anyone how they work, and to run them only occasionally. Ie. once a week, ban half of users who are running xmrig.exe. Also include users who signed up with the same email address, phone number or IP address as the detected users and who have a consistently high CPU use - these are probably successful bypasses of your simple process name based filter.
That way bad actors have a very hard time figuring out exactly what your protections are or how they work. If they were to get an immediate ban as soon as they fired up xmrig.exe, then they'd quickly think to rename it or recompile it or run it under wine or a host of other ideas. Yet having a random selection of their accounts banned seemingly at random means they learn nothing.
Obviously you need a process for users accidentally caught in the net to get their accounts reactivated, and if you're a service like githuib you should probably let the user have a grace period to do that before killing their entire business...