It causes a bunch of weird controller errors, such as when a controller disconnects (or if the deck goes to sleep), it can’t reconnect again.
Just let it use the default version (which I believe should be Proton Hotfix, or whatever Valve decides it should be since BG3 is an AAA headliner, they’ll want this to work)
Maybe try turning steam input on or off? That’s the first toggle I’d reach for with controller issues (like when Elden Ring came out).