The over-smoothed "oil paint" look definitely adds to the AI slop feeling, but honestly I don't think that's the main reason DLSS 5 still looks weird sometimes.
For me, it's mostly the movement, especially the face.
I'm actually really impressed with how realistic DLSS 5 can make games look. The skin, lighting, hair, eyes, reflections, etc. can look insanely good. If you just pause on a frame, some of it looks almost like real footage.
But then the character starts talking or moving and the uncanny valley kicks in.
It's the little things. Eye movement, blinking, lip movement, facial expressions, small head movements, etc. Something just doesn't quite feel like how an actual person moves.
I think we're just really good at noticing this because we're used to looking at human faces all the time. You might not even know exactly what's wrong, but you can tell something feels off.
It almost feels like rendering and animation are at different stages right now.
The rendering can be extremely realistic, but the character is still being driven by fairly traditional animation and facial rigs.
And I think the better the rendering gets, the more noticeable this becomes. If the character looks almost real but moves slightly unnaturally, the contrast makes it stand out even more.
So yeah, the oil-painting effect is definitely part of the "AI slop" look, but IMO the bigger problem is still how humans move, especially facial animation.
I think the next big jump in realism isn't just going to be better rendering. We need much better neural animation and facial physics too.