Whenever I see this manga, I can never shake the feeling that something is just off about the art, but I can't put my finger on what specifically.
It's not like it's bad art. I'd even say the art goes above and beyond by isekai manga standards.
It's like the lines are too pristine, too clean, while somehow simultaneously seeming organic and impossibly intricate.
Maybe it's just the uncanny valley in action; an art style that's not quite anime, but not quite realistic.