You can now play Dead by Daylight on Steam Deck Steam OS at 60 FPS on high settings, with a little bit of work.
Unfortunately this only works on the Epic Games Store version of Dead by Daylight through the Heroic Games Launcher. We have tried this with the Steam version and we can't get it to work and the same goes for the EGS version directly.
Here's the text guide for how to install Dead By Daylight on Steam OS
First off, install the Heroic Games launcher in Desktop Mode, then you want to add it as a non-steam game to Steam for later.
Next, sign into the Heroic Games Launcher in Desktop mode or Game mode and install Dead by Daylight, take note of the install path as you will need this once it's complete.
In Steam Deck desktop mode. go to the install directory of Dead by Daylight, at the top level, copy the entire Easy Anti Cheat folder
Navigate to Dead by Daylight -> binaries -> EGS and paste the folder inside the EGS folder
Go back to the Heroic games launcher and open the properties for the Dead by Daylight game
Set the Wine version to Proton - Proton - Experimental
Tick the EasyAntiCheat Runtime box
Now you should be able to run Dead by Daylight in Desktop or Game mode with no further issues.