Facebook says one hundred API users may have improperly accessed user data
The Facebook blog post would probably be a better source, since it explains the nature of the data:
 https://developers.facebook.com/blog/post/2019/11/05/changes...I.e. apps added to a group by an admin could get some metadata about members of the group.(That blog post would also have been harder to mis-interpret than the NBC article. Half the early comments seem to think that this was about Facebook engineers improperly accessing data.)