The consensus here seems to always be leave in SDR and use match content, but I’ve had no issues with leaving Dolby Vision on all the time. SDR content like youtube and TV shows that were never mastered in HDR look 100% fine to me. Part of the Dolby Vision spec is that it forces your TV into it’s most color accurate settings so why wouldn’t I want that as well? Using an LG C2 by the way.
This is just straight up about colorspace I think. Playing SDR content while forcing the TV into HDR forces the SDR colorsspace which is rec 709 or rec 2020 into HDR which is rec 2020 as well. SDR content for Rec 709 would be forced to artificially spread into rec 2020 but this might be solved by some TVs detecting this? Not sure if they do tho because of the forced HDR.