If you're attempting to play on the Steam Deck and notice that sometimes your controls jitter and eventually get stuck until its unplayable, it seems that RE4 doesn't handle kbm and controller inputs simultaneously very well on the Steam Deck, in order to play smoothly do the following.

Starting from the game page:

1. Go to game properties > compatibility > check 'force use of specific compatibility tool' > enable proton experimental.

2. The touch screen also messed with the controls, so go to the controller icon > edit layout > action sets > default > add always-on command > system > choose 'Touchscreen Off'

3. To ensure there's no issues between keyboard and controller inputs, remove the Escape command from the L5 button as well.

Have to see how long it holds up but fingers crossed its a permanent fix.

Note: It seems like using the volume buttons also stutter the controls (they probably emulate volume keys on a keyboard), but adjusting volume via the quick menu is okay.