this is new behavior that started somewhere in late december. Noticed on deck f43.20251231
The trackpad acts as a mouse at all times, steam-input on or off. when the trackpad has a function in a game, it will act on both types of input at the same time. F.ex. tsushuma trackpad swiped both draw weapon and move camera.
It does not behave like the typical steam-input errors where it switches from controller to KB/M incessantly. It acts as both simultanously, but ignores clicks if not mapped in steam-input template.
I've checked my global steam controller mapping as well as each game this affects.
rolling back to deck-f43.20251210 has resolved the problem for now.