Why does she act like a teenager? Is she mentally stunted?

She can be petty and annoying but might also be a sweetheart. her mjsic however is jorrendous, not thay hou asled, just sahing.

When you listen to her speak, she seems to be on the spectrum. But, also, when you have been a celebrity since your early teens, you both grow up too soon in some aspects, but also stop developing in others.

Yes she is. Quite clearly so.