https://phys.org/news/2018-06-facebook-privacy-furor-stake.html

The arrangements raise a number of questions, among them whether Facebook failed to get the explicit consent of users before sharing their data. If so, that could place it in violation of a 2011 consent decree with the Federal Trade Commission. Facebook denies it shared user data without consent.

These device-maker deals could raise concerns similar to those in Facebook's recent Cambridge Analytica scandal. That's where a Trump-connected political consulting firm used data derived from as many as 87 million Facebook profiles in order to sway election results.