[Feature Request] Steam Deck OLED internal screen is not recognized as true HDR in Desktop Mode

[nicocarbone]

Your system information

• Steam client version: 1773983034
• SteamOS version: 3.8.0
• 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:

In the latest SteamOS Preview for Steam Deck OLED, the desktop session has moved to Wayland and KDE 6.4. This should enable HDR support within the desktop environment. However, the internal OLED screen is not recognized as a true HDR display. The only option available is EDR (Extended Dynamic Range). This prevents the ability to calibrate HDR peak brightness and manage other HDR-specific metadata.

Furthermore, when EDR is active, HDR content (e.g., YouTube HDR videos in Firefox) exhibits clipped highlights, while SDR content appears oversaturated.

Steps for reproducing this issue:

1. Go to Desktop Session
2. System Settings -> Display & Monitor
3. Observe that "Enable HDR" and "Calibrate display" are missing, and only "Enable EDR" is available.