Same issue, but an interesting wrinkle with mine. LG C9, same update as everyone and Dolby Vision is broken between my Apple TV 4K and Denon AVR.
what is interesting is Dolby Vision runs just fine between my Sony UHD player running through the same Denon to the same TV.
So it has to be something specific to the LG and the Apple TV 4K (I have the 2021 Apple TV 4K by the way).