There is court testimony it was drug testing - https://www.reuters.com/article/business/britney-spears-hook...
Can you link your source?
I'd say it was part of some sort of manic/meltdown episode with multiple things going on with some logic. She was under a conservatorship for good reason, it's not some Deep State conspiracy.
I'd like to hear her explanation in her words.
[edit] - From her book
I went into a hair salon, and I took the clippers, and I shaved off all my hair.
Everyone thought it was hilarious. Look how crazy she is! Even my parents acted embarrassed by me. But nobody seemed to understand that I was simply out of my mind with grief. My children had been taken away from me.
With my head shaved, everyone was scared of me, even my mom. No one would talk to me anymore because I was too ugly.
My long hair was a big part of what people liked—I knew that. I knew a lot of guys thought long hair was hot.
Shaving my head was a way of saying to the world: Fuck you. You want me to be pretty for you? Fuck you. You want me to be good for you? Fuck you. You want me to be your dream girl? Fuck you. I’d been the good girl for years. I’d smiled politely while TV show hosts leered at my breasts, while American parents said I was destroying their children by wearing a crop top, while executives patted my hand condescendingly and second-guessed my career choices even though I’d sold millions of records, while my family acted like I was evil. And I was tired of it.
At the end of the day, I didn’t care. All I wanted to do was see my boys. It made me sick thinking about the hours, the days, the weeks I missed with them. My most special moments in life were taking naps with my children. That’s the closest I’ve ever felt to God—taking naps with my precious babies, smelling their hair, holding their tiny hands.