Asunixe basically non Xbox controllers depend on games or Steam implementing PS controllers (thank Microsoft for that)
So when playing a non Steam game with no PS controller support you either have to tell Steam to not touch your controller or exit Steam.
I used to use DS4Windows which kinda does what Steam does but at a system level instead of having it available on Steam games only so I had it completely disabled on Steam.
If that's not your case then simply exit Steam when booting up Plutonium or whatever