this is illegal under GDPR for two reasons: opt-in gained with privacy policy v1 are not valid if gets updated. and you need to opt in by choice not because is the only option
in this PR piece the "political" point (by political I don't mean electoral, but power above communities and indivuduals) still miss. The algorithms decides what a facebook user will see. what become viral, what is trustworthy and what is not. this is never mentioned in the transparency promises, and still, transparency would not be enough (too many unaccountable variables in the neural network).
People should get chronological ordered content in machine readable format. client side, your personalization algorithm would decide which priorities give. I work for this, and I feel is there where the true challenge is. If you want to hack on this, please follow up on this comment.