A main character who is super cutesy and incompetant. (Unless they are a literal child) I have no issue with sweet, dumb characters who struggle with things, it's specifically the affected cutesy behavior that no adult human actually acts like. (Little gasps at slightest effort, running with arms back and knees together, shrieks in horror at slightest even, constantly eating sweet food, saucer eyes)
It comes in pretty much all genres, but it usually feels like this weird, often horny, fantasy about a type of person who doesn't actually exist. There's the personal taste of liking motivated characters who move the plot forward, but it's also just a style of character that makes me deeply uncomfortable, though the exact reasons are often genre specific.
No hate for people for whom this is a plus. I think we all daydream about types of people who aren't super realistic