Finally got tired of my Windows 11 install, and I considered a Linux move. For years and years, I tried to move over, even all the way back in the Ubuntu 16.04 days, even daily drove for a few months, but there would always be something that would make me move back (including but not limited to HDR, support for my old iPod, Outlook calendars, so on). However, on my most recent attempt (running Arch and KDE) things just... work? Yeah, some command line trickery is needed for stuff like HDR gaming (and turns out the screenshots work now, they just get downsampled to SDR by Steam), but this works so so much better than my previous attempts to move over. In recent years, the experience is just so much more polished than it used to be. The situation is no longer "that won't work", it is "you can do that, with some minor tweaks". All my Steam games work nearly perfectly, with only a few changes like Proton GE needed. There are now even improvements like how text on my QD-OLED monitor (which is notoriously fuzzy on Windows) is crisp and clear, or how my Xbox controller's screenshot button works over Bluetooth on Steam unlike Windows which ignores the button entirely over Bluetooth. Things are really looking up!
Yup, was using Spectacle, behaviour was similar to your description. I guess maybe the HDR highlights just got more blown out on higher brightness displays?