The one that annoys me the most is non-linear sentences.
Sailus scratches his head as he pats his belly, while eyeing the vampire's wine glass filled with blood as a butterfly flew around the room.
Sailus scratches his head and pats his belly. He eyes the vampire's wine glass filled with blood.
In another part of the room, a butterfly flaps its wings. In another part of the world, a shitty brat claps some anonymous cheeks. This is the butterfly effect.
There is no objectively bad prose. The closest thing is something that is incomprehensible to an audience. I prefer simplistic writing. If I had to choose between Assu's flowery writing or an average isekai story, I'd pick the latter.