For all the people who are complaining about the mc acting like a loser, I just have one thing to say. Even if your appearance change over night your personality don't. The mc's character, insecurities and trauma are still there. Even after his appearance has changed he's still pessimistic and has a low self-esteem. And considering he has 0 interaction with anyone after he became good looking and op, it's understandable. He doesn't know he's good looking (didn't look in a mirror) and he doesn't know what people think of him after the change.
Actually I like this better, rather than his character having an abnormal switch, it would be better for him to have a character development after he starts to interact with the people in the other world and his own world.