When enabling Game Mode on the Samsung QN90A (50" model) so VRR is enabled HDR isn't detected by the TV. Windows and the Radeon drivers do report 10-bit YCBR4:4:4 or RGB output @at 120 Hz with VRR enabled, but the TV reports HDR disabled but Freesync Premium Pro enabled. In this case the colors & gamma values are way out of wack, producing very dark images. You can imagine how much money I spent on both these devices only to find it not working as intended. These are my settings:
You are using Freesync (aka Adaptive Sync Compatible). Maybe your Tv does not support Freesync with HDR, like the LG CX does not support Dolby Vision with Freesync.
When you use the real "HDMI Forum VRR", the driver would say "VRR" and not "Adaptive Sync Compatible".