The relevant bit is this one here:

It's hard to argue that buying something on a digital platform is not a contract between the user and the platform.

They are deliberately misinterpreting that law. This law only applies for data that they no longer have a legitimate reason to retain. It's not just a rolling 3-year counter that starts every time you log out and gets reset every time you log in.

I haven't logged into Facebook in well more than 3 years they haven't deleted my data and that isn't a violation, I haven't deleted my account (I can't I've forgotten the password and no longer have access to the original email, it's my problem).

It's only for things now lapsed gym memberships, or car dealerships keeping your data after you purchase a vehicle from them. They can keep that data for 3 years and then they have to delete it.