Every PC I’ve ever used automatically detects and adjusts resolution to the display you connect to it. Even Nintendo Switch will detect when it’s docked and automatically adjust the display resolution. But on Steam Deck you literally have to adjust the display resolution for every game, every time you switch displays.
Since getting the SD I have shoved my PC into another room to displace the heat (until I get a mini-split) and I just stream from it to the Deck, whether docked at my desk or on the couch or on the big screen. But this really complicates that process unnecessarily.
This has also not been fixed in Nobara or Chimera.
What’s the limitation there?
Consoles don’t do that, they have a set resolution and try to use that even if the monitor supports higher res, the reason is that a console has a limited hardware and knows its limitations, that way they can ensure the best user experience. The Steam Deck works primarily as a console, but without the usual closed off limitations so you can change the resolution if you know that the specific game you’re trying to play will support it, but as a general the deck plays it safe and uses the same resolution it would use for the integrated screen.
Also you need to think on the cluster fuck it would be if you’re playing the game in 4k then unplug your deck and now you have a 4k game downscaled to fit a 1280x800 screen.