gamepad and mouse input not working on non-steam games

[DocMAX]

i am on arch with a clean system, just gamescope and steam. problem is if i start non-steam games via gamescope, mouse and gamepad inputs work. if i start the game with steam they dont. any idea why?

[kisak-valve]

Hello @DocMAX, this reads more like an issue with the Steam client's Steam Input subsystem than an issue with gamescope.

There's a similar issue reported at ValveSoftware/steam-for-linux#10430. Closing in favor of the older issue report.

[DocMAX]

I "fixed" this by starting gamescope with sddm. Using sddm gamepad input works, why?