The reason why the art is different is because it is a completely different person who's drawing them. For this series its sasaki tamu who's the artist while the other ones are being done by sasaki minoru !
Also which panels look ai to you?
Mostly the close ups on pg 24, 27, 30, 33
I can’t see any hallmarks of AI personally, it could be that an assistant has worked on some of those frames and you’re picking up that it looks like a different “hand” has drawn something, because you’re sensitive to that kind of thing.
Y'all I really like this one, but don't some panels seem like they could be ai? I hope it's just me being paranoid, but I'm pretty good at discerning ai generated content. The art is also pretty different from the author's other works. I really hope I'm wrong.