I wanted to write this because I was trying to get DOOM 2016 to run at 60fps on my deck oled using a DRS mod described in detail in a digital foundry video, and I followed all the steps... and it didn't work
And then coincidentially I tried setting up Bad Company 2's post EA shutdown multiplayer mod on, followed all the steps... same thing
And I noticed there was a common thread: "dinput8.dll". So I looked into it. It turns out that many mods use dinput8.dll to inject custom code. I was able to follow a google/reddit rabbit hole to find this post:
https://www.reddit.com/r/SteamDeck/comments/ubxhbw/any_guide_how_to_install_nfs_underground_2_with/
Tldr the fix for broken dinput8.dll mods is this:
-Go to desktop mode
-Use proton tricks
-Navigate to the game prefix
-Select default
-Run winecfg
-Select Libraties, then add an override for dinput8 selecting it from the drop-down and use the "native and then built-in" option
-Click apply and then exit
This should fix any mod that uses dinput8.dll! Some mods also may override other library modules, and presumably this would work on those as well, but I haven't been able to confirm yet.
If anyone wants links or help with bad company 2 or tuning DOOM 2016 performance as well comment below and I can add more info!