https://www.cnet.com/news/facebook-shuts-down-ios-research-app-it-used-to-access-user-data/

Apple confirmed that the app violated its policies.

"We designed our Enterprise Developer Program solely for the internal distribution of apps within an organization," Apple said in an emailed statement. "Facebook has been using their membership to distribute a data-collecting app to consumers, which is a clear breach of their agreement with Apple."