I have always wondered that. In FTR Britney speaks and acts like a grown up mature woman who is well aware of her mistakes, her learnings and how she will move forward. In IATFF she is just plain robot. And then through IABJ / POM 1.0 she goes from robot to rebel (feeling everything, putting messages on her body and giving us killer shows that lead to POM 2.0) and then suddenly all massive ticks and childish manners start showing up.
People do change their behaviours, but not their personalities and body language. And it feels like everything around her is designed to keep her under so much control, that they have been creating more mental issues than she actually had. Even with memory loss... Britney thinking Will came up with "It's Britney *****" or saying "Oops" is just a song, clearly show that her mind is cloudy. It is not something you just randomly forget... "It's Britney *****" was on her lead single from one of her most praised albums, it was on the VMA's performance she regrets the most, she said it every POM performance; it is not a hard thing to remember that it belongs to Blackout, 2007 and what the writing process was with Danja. We are talking about "Gimme More", not about "I'll never stop loving you" or any other random album track. It is not a random memory lapsus, she has cleared been mixing up timelines, losing memory of things, getting VERY drastic body language changes as we see on stage and her videos on Instagram.
Funny enough... didn't this happen with MJ too? With time, he was more and more like a child.
I personally prefer Britney out of the music industry, out of social media and in a ranch in Luisiana with her mother as she said even when she was 17. Let that woman get some peace of mind. Her management doesn't help, help family doesn't help, her fans don't help.