This is an issue both for YouTube and YouTube TV for myself as well. I keep “Match Dynamic Range” turned off to keep my TV from switching in and out of something…. My TV will normally pause with Apple and indicate if it’s receiving an HDR or DolbyVision signal. With YouTube I just get the pauses…. Even when just changing a channel.
When I want DolbyVision for Netflix or my library, I turn the match dynamic range back on.
Honestly, no other app behaves that way on my ATV.