I have 2 computers connected to my Xiaomi Mi Monitor 34" Ultrawide Curved Gaming via HDMI:
1) KDE Slimbook 14
2) Steam Deck

Both computers are running Arch Linux (Steam Deck is not running SteamOS, but upstream Arch Linux), with Plasma 5.26.2.

I configured the monitor to display both inputs at the same time (split screen), and when they try to display the same color, what is shown in the monitor is different. Pictures attached.

What could be causing this?

Night Color is off on both computers, and so is color correction (at least I think it is, none of them have the colord package).

Update: I think there is a bug in the amdgpu module that affects the KDE Slimbook computer, because even in console (non-graphical), the colors are different. Picture attached.