I did enable FreeSync and DRI 3 just as generally good things to do, still didn’t fix the problem.
What’s strange is that I can force 3840x1080 @ 240 hz and it works just fine.
I briefly thought I would go back to Windows after about a decade, spent 45 minutes on it, decided I can live with 120 hz for now if it means not using it because of how awful everything was. “Oh cool, I can install an actual Linux system on Windows and even mount my ext4 drives? That’s pretty cool… Oh wait… I need to sign up for Windows insider and transmit data on everything I do back to Microsoft if I want wsl 2. This is ridiculous.”
I feel like this is one of those things that’s just going to be broken. Maybe as displays like this become more common it’ll get looked at, but if anyone comes by with a Samsung Odyssey G9 and actually has 5120x1440 @ 240hz, please do reply!