Sorry but other than the fact that the content is coming from YouTubes servers and subject to their encoding none of what you say is truly accurate.
Please reread my post here:
”Well it’s an application built using Apple Tools running on Apple hardware - so I’m afraid there is plenty of room for a problem with HDR10 / rec709 originated content being displayed improperly to be a problem with Apples toolset or YouTubes coding or a combination of both.”
Also the “app” comes from Apples servers but I would doubt that would ever cause this kind of problem.
In both cases YouTubes app both clearly sees the metadata correctly as rec709 encoding yet the problem only appears using the Apple native app. From a simple signal flow point of view there’s plenty of room for the problem to occur in Apples sdk, in tvOS itself or as a result of bad coding on YouTubes part.
I was simply asking a question here hoping to find someone knowledgeable enough who could speak to the problem without the standard “Not Apples problem” fanboy reply which seems to be a defining characteristic of anyone here rated above a two helpfulness or whatever that parameter in your profile is supposed to indicate.
Helpful tip: In life it helps to assume nothing until proven otherwise.
Please don’t waste any more of you valuable time on this - clearly you have other “Not Apples fault” messages to convey to the masses.