The findings are consistent with our own attempts. While iPhones running iOS 13.2.2 indeed show the camera actively working in the background, the issue doesn’t appear to affect iOS 13.1.3. We further noticed the issue only occurs if you have given the Facebook app access to your camera. If not, it appears the Facebook app tries to access it, but iOS blocks the attempt.
It remains unclear if this is expected behavior or simply a bug in the software for iOS (we all know what Facebook will say; spoiler: “Muh, duh, guh, it’s a bug. We sorry.”). For what it’s worth, we’ve been unable to reproduce the issue on Android (version 10, used on Google Pixel 4).
------ “There is no fate that cannot be surmounted by scorn.” -Albert Camus