Switching to desktop while docked to an external display with HDR enabled leads to incorrect desktop colorspace on both panels

[matte-schwartz]

Your system information

• Steam client version: 1731990050
• SteamOS version: SteamOS staging 20241112.10000, SteamOS Main 20241114.1000
• Opted into Steam client beta?: Yes
• Opted into SteamOS beta?: Yes
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

When my Steam Deck OLED is docked to an external monitor (AW3423DW, HDR-capable) via the official Steam Deck dock, and if HDR is enabled on my external monitor in gamescope-session, switching to desktop mode leads to a washed out Plasma desktop on the OLED Deck's internal panel and an over-saturated desktop on the external monitor. This happens across X11 and Wayland desktop in both Plasma 5.27.10 (SteamOS Main) and Plasma 6.2.2 (SteamOS staging).

If I disable HDR on the external monitor before switching to desktop, then both panels have the correct colorspace on Plasma desktop.

Internal panel:

Washed out:

Correct:

External panel:

Over-saturated:

Correct:

One other note is that this issue is not present on my ROG Ally, which has a non-HDR internal panel. I can leave HDR enabled in gamescope-session and switch to desktop without this occurring on Arch Linux, Plasma 6.2.3 and Kernel 6.12.0. At some point I'll try to check this same set up on my OLED Deck to see if it's truly a SteamOS issue or if it also happens upstream as well.

Steps for reproducing this issue:

1. Dock a Steam Deck OLED to an external monitor that is HDR capable via the Steam Deck official dock
2. Enable HDR in the right-side Steam menu
3. Switch to either an X11 or Wayland desktop session from gamescope-session

The colorspace should visually look incorrect at this point.

Here is a system report captured after step 3:

report.txt