macos / windows brightness issue in HDR

[ulyssecochard]

hi !

Describe the bug
I have seen lots of issue regarding HDR, but I am just adding one for this specific setup.
TL;DR : brightness is screwed up. Both in games or in content consomption (HDR test videos)

Screenshots

here is the same image of the windows hdr calibration tool, one streamed the other is direcly dislpayed to the screen.
As you can see, you don't even see the calibration stripes. It's not a issue of the photo, it's the same IRL.

Host computer : windows 11 24h2
(RTX 4080/ R9 5900X)
Sunshine 0,23,1
HDR turned on in the setting menu
HDMI 2,1 -> G8

client : macos sequoia 15.2
macbook pro. 14 m1 pro (2021)
moonlight 6,1,0
HDR turned on in the setting menu (I also tried to turn it off, with no visible changes)
DP 1,4 -> G8

monitor :
Odyssey G8 oled
HDR turned on

Moonlight
HDR turned on (obviously)
Vsync on
4:4:4 on
bitrate uncaped