Redfall can run extremely well on the Steam Deck, providing you get the settings right, if not, it will be a stuttery mess.

First off you want to set the quality preset to low.

Turn off motion blur and v-sync

Enable upscaling and set to AMD FidelityFX SuperResolution 2.1 to Quality

Set Upscaling sharpening to 0.2

On the Steam Deck, open the quick menu, under performance set the Framerate Limit to 60 and tick the allow tearing option.

Now you should be good to go.