Kitty will be reverting back to when her powers first awakened, so there will be a lot of accidental phasing. She’ll be dropping a lot of things, maybe getting stuck in a door or two. And while she’ll be the same mentally, she might not realize that things have been reversed (or she won’t realize that she‘s been affected), so her first thought might be that she’s losing control of her powers. Which is her one big fear, so uh....she might need a bit of help calming down.