Observation. #VLC does not appear to support #HDR on #Linux, but #MPV does. I'm using the Celluloid front-end, but both it and the more basic MPV player both look great. VLC does not. I've poked around in the settings for VLC and can't seem to find anything. You'd think it would least tone map the video properly so it would look close, but it really doesn't look great.