From GPU Open:
https://gpuopen.com/fidelityfx-superresolution/
Just look at the vaseline effect on the grass
Top of the mech warrior guy has some weird artifacting. E.g. on his left shoulder there is a vent and FSR blurs all the details.
The plants have lost a lot of detail
Specular highlights on the rock below the bird are gone.
If you download the high res originals images then you see many more problems.
For example, the big palm tree bottom right is pixelated and soft.
Will try and get more exampels later, but things like fine details of hairs, wires andare also problematic for FSR because it simply doens;t have the samples to reconstruct.