Did a quick check with the latest AppleTV 4K connected to the Soundcenter (HDMI D) and had it configured as per the instructions (4K SDR, Match content On).
When I play a movie from Netflix that is Dolby Vision, the panel signal that it is indeed Dolby Vision being played.
Thanks for checking.
With my 2017 ATV4K connected to HDMI A in the Sound Center the screen also report Dolby Vision, when playing movie from ATV+.
However the latest ATV4K should be able to decode Dolby Vision at 60 fps – something the 2017 cannot.
The YouTube app on the new ATV4K should also be able to play HDR at 60 fps if you force it to HDR – match function does not yet work on YouTube. In the YouTube app you can see the actual frame rate if you turn on statistics.
Maybe there will be a difference in frame rate between Sound Center input and input directly to the screen.