1280x800 resolution on external display not working while in Desktop Mode

[dragon99919]

Your system information

• Steam client version: Steam Deck Stable / 1721173382
• SteamOS version: 3.5.19
• Opted into Steam client beta?: No
• Opted into SteamOS beta?: No
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

When changing external monitor resolution to one matching SteamDeck internal resolution which is 1280x800, the display just says 'out of range', despite working with the same aspect ratio on other resolution, and 1280x800 working in different distros (Linux Mint 22 for example has no issues). Tried with two docks - official one and a random one I used for my phone, along with different monitor and even HDMI cable.

Steps for reproducing this issue:

1. Plug in Steam Deck to Dock and power it on, then go to desktop mode.
2. Go to Display Configuration and change the resolution of external display to 1280x800.
3. Apply changes.