UPDATE: I think I found the probelm, and I'm curious if you guys have also come accross this weird bug:
I currently own two Hisense TV's - a 55"
Q8600 and a 55"
U7QF. Unfortunately, neither supports Disney+ so I had to buy an external Android TV box. No matter the HDMI source (and I've tried multiple devices), the TV seems to get "stuck" in the BT.2020 color space after viewing HDR content, and then proceeds to apply BT.2020 to
everything ... the UI, SDR (BT.709) content, the lot. It doesn't switch between applicable colour spaces at it should.
This causes the whole picture, to get over-saturated in the red channel. This is very noticeable on skin tones and other scenes where BT.709 is expected, but BT.2020 is applied ... and there's no way to actually manually force the HDMI input either way. Changing the output from the Android box doesn't help either, save for using HDR to SDR mode, but that defeats the purpose of having an HDR capable device, and also it makes content look really ugly.
The problem is on the TV's side, and the only way to "reset" the picture back to BT.709, is to either pull the HDMI cable out and replug it, or to go into the Hisense menu and change the picture profile to something else, and then change it back again ... that seems to trigger a BT.2020 to BT.709 switch-over, but it's quite cumbersome to have to do this every time.
I already flashed the TV firmware with the latest M0222 build, but that didn't solve the problem. I've written to Hisense support, so hopefully they'll come back to me, or the
@Hisense rep here, if still active.