This may be a “no duh” post, but recently I turned off HDR on my 2nd gen 4K Apple TV. I’m running a TCL 65” 4 series. It has hdr 10 but it’s not FALD. I always had HDR on because it felt like that gave me the best image. I was shocked when I turned it off and got better color accuracy and better contrast out of the tv. Feels like a gimme that you shouldn’t use HDR without FALD or Mini LED, but I am much happier with the setup now
Same with my Samsung TV. While some films look a bit worse with HDR off, for the most part everything else looks better.
War of the Worlds looks almost washed out and over exposed with HDR off, but Avatar: The Way of Water looks better with it off. Go figure.