From my limited research and understanding, Nvidia makes Linux drivers, but they’re closed source. These work fine. They open sourced some stuff but not enough to really change much yet.
There are also FOSS drivers, but the performance for those vary.
Is this correct? Should I stick to proprietary drivers if I want consistent performance?
In general, anti-cheat software is always a show stopper. There are a small handful of exceptions, growing mainly due publishers trying to get their games working on Steam Deck. Most of the time, this incompatibility is employed as deliberate anti-competitive corporate practice. Some anti-cheat vendors like EAC have made moves towards Linux compatibility, but publishers must opt-in and most refuse even when the option is on the table.
I've become much less of a GNU zealot over the years, but anti-cheat software makes me go full Stallman. These things are just rootkits. They do nothing but cause inconvenience to the end user, just so some child gambling company masquerading as a game studio can cut operating expenses for their massive cash-cow gaming platforms.
Yeah, I hate that shit. Thankfully, I trained my brain to hate non co-op multiplayer games. Anything competitive gets like 2 days max and then I delete it and play more Monster Hunter or something single-player. I think Splatoon 2 was the last competitive game I played for double digit hours.