FSR on PC, assuming you're not using an Nvidia gpu (before 2.6) has always been a lie, Wuwa's FSR isn't real on PC. No wonder Genshin's FSR 2 looked better than wuwa's FSR. The image looks identical when you have:
Left image: FSR ON without modifying the Engine.ini file
Right image: FSR OFF while setting base resolution to 77% by setting r.SecondaryScreenPercentage.GameViewport=77 in Engine.ini
I think all the FSR toggle does on PC is divide the base resolution by 1.3 (100/1.3~=77), it's not actually FSR, it's just using UE4's garbage temporal anti-aliasing upscaler. Obviously this becomes irrelevant once 2.6 drops with actual FSR 3. FSR 3 released in 2023, there is no excuse for any modern game to not have FSR 3, unless the dev sold out to Nvidia.