Struggling to understand #HDR and how this is supposed to look without having references is really hard. Especially on Linux PC where support for anything HDR is rather new.
This is e.g. screenshots from #Metro Exodus played via #Proton Experimental on #Wayland and #GNOME 49 (all on lowest(!) gamma).
HDR OFF is okayish but looses a lot of details in the dark
HDR ON is washed out (known bug for game?)
HDR ON + ReShade with LevelsPlus. Looses some highlights but is IMHO best "readable"

