Would like to add this happens on Windows 11 as well, and MacOS Ventura, so it doesn't appear to be platform specific. I'm aware this is specifically steam for linux, just figured I'd point it out.
Go to Steam Settings > Interface, then set "Start up location" from "Store" to " Library" (im pretty sure it should be the same on linux I dont have my linux pc with me right now)
I was experiencing the same problem on Windows (win 10) steam, where it would launch briefly in small mode before kicking back to large mode. Doing this helped fix it for now.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Ever since the new UI, it doesn't actually start "properly" in Small Mode. There's a brief moment right after startup where the Small Mode UI is visible, but then the app automatically switches back to Large Mode, generally showing something from the Store page, so I've got to switch back to Small Mode with every app startup.
Steps for reproducing this issue: