Hello @zbychpantuch, you've described an issue with the Steam client instead of SteamOS as a platform, so I've transferred this issue to the steam-for-linux issue tracker. I recall reading a similar issue report before, but didn't find the older issue report in a timely manner.
Still present on 3.5.19
I also started noticing this, at first I thought the display resolution was low but the art is sharp when you are not highlighting it, and it is more noticeable if the art is actually high resolution.
Seems to be duplicate of https://github.com/ValveSoftware/steam-for-linux/issues/6596
Your system information
Steamdeck OLED 512gb
Please describe your issue in as much detail as possible:
When library or home game capsule in steamOS gaming mode is brought into focus, it gets slight blur (among other default effects). This blur makes the capsule art lose sharpness and is most likely an unintended effect
Steps for reproducing this issue: