Why would it be a GDPR violation? As I understood it, the point of the GDPR is to prevent people from being tracked without knowing about it and consenting to it. Here the consent button is as obvious as it could be, you really can't miss it.
I don't care much about this case in particular, because I don't use their pages much anyway, but from my understanding, the correct approach would be, to simply use ads without tracking for the people who don't consent.