Could you post a screenshot with HDR enabled? The LG monitors have it but they are all Freesync.
That's hard to do. There isn't an easy way to do HDR screenshots.
That video above isn't great BTW. It's HDR, but something is off, and they don't really show much in the game.
Nevermind, it appears to be an issue with Firefox. Firefox shows that it's streaming Youtube in HDR, but it's just passing it all SDR. Need to use Edge.