As a recap, users found out Facebook was opening the camera in the background due to a bug that shows the camera feed in a tiny sliver on the left side of your screen when you open a photo in the app and swipe down. We were able to replicate the issue and noticed it only happened if you had given Facebook permission to use your camera. Obviously, that permission is not meant to extend to the app using your camera in an unsolicited manner.
— Joshua Maddux (@JoshuaMaddux) November 10, 2019 At the time, Facebook noted that this was a bug “where the app partially navigates to the camera screen when a photo is tapped” and that it had no evidence of a photo being uploaded due to this. Nonetheless, it sounds like now seems like a great time to update your Facebook app. Via The Verge