The new Apple TV supports QMS VRR (Quick Media Switching, Variable Refresh Rate) so that when switching from one framerate to another (like 24 to 60Hz) there isn’t a screen blackout.
However, changing resolution or dynamic ranges, still result in blackouts. But why?
I’m thinking this is an HDMI limitation/issue, but why is this not a problem for iPhones or built in apps?
For the exact same reason using the on board built in apps of your smart tv doesn’t either, there’s no HDMI handshake involved.
It’s not the AppleTV that causes the screen blackout, it’s the tv at fault because currently it’s not something the HDMI input can handle.