Firefox doesn't support HDR at all on any platform. https://bugzilla.mozilla.org/show_bug.cgi?id=hdr https://bugzilla.mozilla.org/show_bug.cgi?id=hdr For Edge

Firefox doesn't support HDR at all on any platform. https://bugzilla.mozilla.org/show_bug.cgi?id=hdr https://bugzilla.mozilla.org/show_bug.cgi?id=hdr For Edge and Chrome I'm surprised it doesn't work for you with HDR enabled in the OS, but did you by chance turn the SDR brightness all the way up in the OS settings as well? Since desktop OLED displays are not very bright you might have done this. And if so then there's simply no more brightness range left for HDR to use, so you basically have an SDR display at that point regardless. That said, Windows also has by far the worst HDR support of any platform. Possibly because they were one of the first so everyone else got to learn from their mistakes, but they also haven't seemingly tried to fix it, either, which is odd