Why Flutter Apprentice is not for free?

Hi everyone, I read this on flutter.dev

But when I try to get the book it says that is not for free even if the current date (15/12/2021) is before 06/01/2022.

Is this a bug? How can I solve it?

Thanks

Once you have created an account you can visit this page to see the book Flutter Apprentice | raywenderlich.com