I guess it is not unusual that people have the steam launcher in the background running.
Playing with mouse and keyboard goes smoothly but when Steam is running and I play with Xbox Series X gamepad connected via USB-C Cable connection Button A Opens the chat instead of triggering the basic skill while standing still, when I move in any direction while pressing A the Basic Skill is triggered and Chat stays closed.
Tested with Steam on and off and it seems like Steam is overriding parts of the Controller Settings in Diablo4 while in Background.
Is this something that needs to be fixed in Steam or Diablo? I dont know but maybe someone should take a look at this 