No no I get ur part about being too OP but the only thing I hate about Subaru and this MC is their selfishness and the way they solve things in a very irrational way. The MC's almost broke his relationship with his trusted members when he can just do the hero thing and go back to his hometown while still having good allies on his back and knowing something stronger like the demon can pretty much beat him easily, he needs more than his just strength.
For Subaru the guy literally thinks his in a romcom and already knowing he has potential he still doesn't gets the backbone to do something or atleast learn to defend himself and rather not having the other girls save him. He doesn't even got the mind to atleast know more about Emillia (idk if I got the girl's name right) and only just think she is cute and pretty. If he wants to protect Emillia then he got to atleast know more about her in a wider stance. He doesn't even probably know that Emillia's familliar creature is more than just a mythical creature.