The AI art is just not very good. I mean, look at this:
She's very clearly NOT lying on the poolside, her sprite has simply been superimposed over the background, like she's lying on top of a matte painting. For crying out loud, the shadows of the trees cast on the tiles aren't even extending onto her leg! That is such an obvious thing to see, but they overlooked it.
The first CG isn't very good either:
Her thighs are moving up and down, her tits are jiggling, but there's absolutely no motion of the head or the hair, like it's made out of plastic. It looks very uncanny. Live2D animation needs more effort than you might expect. Also, that one really exemplifies how the shading of the AI character model completely clashes with the utterly-flat and unshaded background.
Needs a lot of work.