https://www.sfchronicle.com/business/article/Apple-busts-Facebook-for-data-sucking-app-13575136.php

Apple says Facebook can no longer distribute an app that paid users, including teenagers, to extensively track their phone and web use.

TechCrunch reported that Facebook paid about $20 a month to users of the Facebook Research app. While Facebook says this was done with permission, the company has a history of defining “permission” loosely and obscuring what data it collects.