I was never bullied at school.
Always had lots of friends.
High achiever academically, and found it easy.
Teachers never targeted me as I was pretty good really, and there were far easier, and more deserving targets.
But….I still disliked school mostly, and would have preferred occasional days on my own in my room pretending to be ill if I could ever get away with it. Didn’t really ever happen though, as it was ingrained that I had to attend.
So OP, there might not be anything wrong, he might just hate (or slightly dislike) school. I’d say that was fairly normal, as back when I was there, it was pretty crappy. It might just be that he needs to learn he has to go regardless.