Like ebg13 said, you need to ask them. That said, I seriously doubt it's GDPR related. It might be pricing, but I'm skeptical that Pearson charges significantly extra for parent accounts.

As someone who had PowerSchool through highschool though, it sucks for students with overprotective parents. Friends who did poorly on an exam would be getting angry texts from their parents before they even got home for the day. Friends who decided to skip a class to have fun would have their parents notified within a few minutes of the start of the class. It's a pretty powerful tool for helicopter parenting, and I would have much preferred if my school didn't have parent accounts. I'd still talk to my parents about school, and tell them when I did badly, but I'd get to bring it up at a good time and handle it in person instead of them knowing my grades often before I did.