4K@60Hz missing over HDMI (only 4K@30Hz available, regression from 3.7)

[Schnurzel700]

Your system information

• Opted into Steam client beta?: Yes
• Opted into SteamOS beta?: Yes
• Have you checked for updates in Settings > System?: Yes
• SteamOS: 3.8.4 (Beta)
• Steam Client: May 7, 2026
• Steam Version: 1778204082
• Client Build: May 8, 2026
• Device: Steam Deck
• Dock: HDMI 2.1
• Display: LG 49UH6109

Issue Description

On SteamOS 3.7, my external display supports 4K @ 60Hz over HDMI.

After updating to SteamOS 3.8.4 (Beta), this is no longer available:

• Only 4K @ 30Hz is shown

This happens in both Gaming Mode and Desktop Mode.

Additionally:

• On SteamOS 3.7, HDR works in Gaming Mode but is not available in Desktop Mode
• On SteamOS 3.8.4, HDR is now available in both Gaming Mode and Desktop Mode

Expected Result

• 4K @ 60Hz should be available as in SteamOS 3.7
• No regression in available refresh rates

Actual Result

• 4K @ 60Hz missing
• Only 4K @ 30Hz available
• HDR newly appears in Desktop Mode

Steps to Reproduce

1. Connect Steam Deck via HDMI dock to LG 49UH6109
2. Open display settings
3. Select resolution -> only 4K @ 30Hz is available

Notes

• Regression started after updating to 3.8.4 Beta
• Same hardware and cable setup as before
• Reproducible consistently

[bbtufty]

Also the case for me, I now default to 1080p@120. Extra weirdly, switching to 4k gives me black bars on the side of my screen as well