https://qz.com/1296373/your-smartphone-was-probably-sharing-your-friends-facebook-data-behind-your-back/

Following the Cambridge Analytica scandal, Facebook promised its users they would have full control over their data, noting that it cut off third-party access to detailed friend information back in 2015. But according to a New York Times story (paywall), Facebook hasn’t been counting mobile devices as third parties, leaving companies like Blackberry, Samsung, and Apple an open door to take and store information without explicit user consent.

The Times found that because of this loophole, a 2013 Blackberry device using a Facebook account with 556 friends could access the data of hundreds of thousands of people without their permission. They report that some devices could get information such as religion, political preferences, or relationship status.