Curious to hear what settings you were using? Because after this steam deck fanatic kept harping about how it was a perfect experience from start to finish if you have the right settings, I went back and tried it on my Deck. In act 3, in a sparsely populated area of the city, I was hovering in the low 20s with frequent dips into the teens. With everything set to low (except textures on mediu) and all the visual flourishes like god rays, bloom, etc disabled. FSR couldn't even improve things.