I'm giving Linux gaming a shot, but I've run into a couple display issues

I'm dual booting PopOS and Windows 11 for now while l try things out. I went with PopOS for the NVIDIA drivers, since I have a NVIDIA card. Installation went smoothly, but setup is where things started to get a little weird.

I have 2 monitors, a main 360hz monitor and a secondary 165hz monitor. I seem to be able to have them both working at the same time in Windows 11 without issue, but in PopOS, setting the refresh rate to 360hz on the first monitor causes both displays to stop working properly. The 360hz monitor will stop displaying picture all-together, and the 165hz monitor will start flickering wildly. Turning off the second monitor brings the 360hz's image back, but then I'm down a monitor. Also, if I set the refresh rate to anything lower than 360hz, they'll both work. I'd like to still be able to use it at the native refresh rate, but I can't seem to find any other solutions or anyone else who seems to have had this same issue.

My second (slightly less annoying) issue is that I can't seem to use HDR in games. Is this normal, or is there something I can do to bring back support?

Also, if PopOS isn't the way to go, please let me know! I tried Nobara first, but immediately had issues with the displays locking up and flickering before I even got it installed.