Quick recap of season 2: (spoilers if you want to read it yourself!)
MC told Sys (the silver haired woman, whom is the personification of the system that was aiding him before) to wipe everyone's memories as he didn't want to be remembered as a hero but lead a normal life. Except she could only wipe the memories, not the influence he had on the world. So some people started noticing something's wrong. The old sorcerer guy came from another parallel dimension where the MC destroyed the world, so he decided to come to the one we're seeing to take revenge on this other (our) version of MC by turning the world against him and trying to kill him. And he's using the doubts of the people that noticed something was wrong to make them think MC is/was the enemy.
I stopped reading this after season 1? Where he saved his mother, who is in the hospital. But what is happening now???? Why is the MC the bad guy now???? I am so confused.