Group FaceTime bug: It is a BUG that fell off the usual test scenarios
The Apple FaceTime bug gets activated in a rare, IMHO weird, scenario - you add your own number when you’re calling someone via FaceTime. It is a difficult bug to test against. Note that Group Facetime, which enabled this bug, was introduced later, after the release of the new iOS. It is suspect that Group FaceTime uses a different protocol than the original 1:1 FaceTime.
Contrast this to Google’s Location Sharing “bug” which ignored the Location Sharing settings, which is easy to test – unless it was intentional, which I suspect it was, until it was caught. Oh, don’t forget the Google Home Mini “bug” that recorded all the audio it can catch - again, this is pretty obvious and easy to test. I use bug in quotes because I believe that it was intended as a feature, until it was caught and revealed to the public, and then classified as a bug.
Regardless of what Apple and Google, and the rest of the technology companies say on how they are doubling down on preventing bugs, nobody can guarantee a 100% bug/error free product/service since these are all complex, man-made systems.