I'm playing Greedfall on Xbox One X at 1080p in SDR.
My display is a carefully calibrated plasma display, which generally displays games and movies perfectly. It passes the built-in xbox video calibration perfectly (ie. black levels and white levels are exactly correct).
Most games look fine. Xbox generally has a slightly odd gamma curve that can tend towards black crush, but that's been the case since 360, and is normal on Xbox consoles.
I run in SDR mode, with video black level (ie. normal/default) ie RGB range 16-235 (aka "limited" RGB) which ensures common calibration across various media types. This is all as per default on xbox one series.
For Greedfall, however, right from the Focus Home Interactive video/logo at the start, the game looks somewhat washed-out. The darkest "black" that is achievable appears dark grey. Maybe Greedfall is attemptiong to apply "limited" RGB correction itself, despite the console doing it, resulting in double-correction in SDR use? Or perhaps Greedfall uses a higher black level because of xbox gamma shift.
Note that the initial Greedfall "splash screen" shown by the xbox dashboard looks beautiful, and is absolutely correct. It is only once the game loads to the Focus video that the black level shift occurs.
Either way, the in-game brightness control doesn't help, as the black level doesn't change - all you can do is push things towards the dark grey.
I can correct this on my video receiver (or xbox) by forcing full-range RGB, but that's not what the xbox is set to output, so everything else looks broken when this is done.
Greedfall is the only game exerperiencing this - I'm also playing Outer Worlds and Bard's Tale 4 at the moment, and both look perfect.
I haven't seen any other reports of this, which is slightly puzzling.
I have registered on the forum to report this - I hope it is of some help. I repeat that I'm only seeing this in Greedfall, so I don't believe it is my console or my AV equipment at fault.