https://phys.org/news/2019-01-facebook-paid-users-track-smartphone.html

The news could be a further embarrassment for Facebook, which has been under heightened scrutiny over failing to crack down on manipulation of its platform and for sharing private data with its business partners.

Facebook said it shut down the application on Apple's iOS on Wednesday after the TechCrunch article was published. It remained unclear if it remained active for Android users.