How is running a game with proton different in Steam and Lutris? - eviltoast

I have had numerous cases where a non-Steam game would run perfectly through Steam with Proton but the same game wouldn’t even launch through Lutris, even though I used the exact same Proton version. How are they different? Is there anything that Steam does in the background that Lutris won’t?

I’d love if anyone could shed some light on this for me.