Mai Sakurajima is one who was in the spotlight at a young age. Then her wish that she mentions that she wishes she could go to a world where nobody knows her. Though as we see what is actually affecting Mai, you can quite see she is not fine by it. These illogical stuff getting referred as puberty syndrome. More than likely, that is what is going on with Mai.
Meanwhile, it seems Puberty Syndrome is affecting both Sakuta & his sister Kaede. We do learn that Sakuta beating up kids and sending them to the hospital, as well as Kaede getting bullied. Everything Sakuta mentions his scar is quite bizarre. Although for Kaede her getting bullied and eventually having trouble communicating. Also, losing her connection to the outside world helped with the puberty syndrome symptoms. Although anyone who has been bullied disconnects from themselves in the world because it feels much safer. Though the one bizarre case is that you see the bruises on her and considering there was no physical bullying according to Sakuta.
The episode ends where it is you get the sense this is taking more and more of a toll on Mai.