HDR can be a hit-or-miss even on Windows though, thanks to the myriad combinations of monitors, cable versions and standards. So hard to give a definite answer

HDR can be a hit-or-miss even on Windows though, thanks to the myriad combinations of monitors, cable versions and standards. So hard to give a definite answer besides "YMMV". In my case though, it works fine without any hiccups. My main setup is a 7800XT, connected to an AOC CQ32G3SE using a DisplayPort 2.1 cable. HDR works fine both in Steam game mode as well as in desktop mode (KDE).