So I have a q85r and dont expect anyone to really have an answer, more this is for the engineers if anyone from samsung reads these posts?
So for HDR content, if my xbox is set up as a game console as the hdmi input, this seems to mess with the hdr settings quite badly, now this TV is a 1500 peak nit set and with the hdmi input set to unknown forza horizon will correctly roll off at 1500 (it eye balls to "corret" at around 1400 but i know this is incorrect)
if i have the input set to game console, forza horizon 4 will roll off the brightness at near 10,000 nits!!! its crazy how incorrect this is, same for devil may cry and some other games where the hdr white point balance is right at the high end. this could possibly be fixed with an update im assuming.
As for the contrast, out the box calibrating on my xbox one the sun logo will always be visible even with it set to 50, to correct this i had to set the R offset to -10 and the G gain to + 6. this seems to fix the issue. this also looked like to my eye and not a calibration tool, to set the white to something more natural where as before it did look like there was too much red, but not the red you see with the warm1 or 2 settings, just incorrect.
when the contast screen 1st appears the sun box will be bright enough to not be shown, but then slowly the sun will appear, its like the backlight or something is undershooting, again possible to fix with an update to fix the white point by default, as noted by a couple reviews of other 2019 sets the colour seems to not be as correct as previous sets
The final point here is a bit of an unknown, while viewing netflix last night the backlight seemed very dim, setting to 50 did nothing, and reducing to 0 did nthing, it was like it was fixed at somewhere abour 20 points. switching inputs again the backlight did nothign what so ever agian. Only when i power cycled the tv did the backlight correct its self, again im sure this could be fixed with an update