A serious software bug in the Facetime software used for video chats on iPhones, iPads, and Macs allowed other users to eavesdrop on you before you were even aware there was an incoming call.
Callers were able to hear audio of what was happening on the other end before the person they were calling was even aware of the call. All the person had to do was call a contact and then swipe up to add themselves to a group chat before the other person answered. Demonstrations of how to listen in have been popping up all over the Internet, which represents a serious privacy concern.
Apple promised a software fix by the end of the week and eventually ended up taking the group chat function offline until they come up with one. So if you haven’t been able to have a group chat, that’s why.
And be aware there’s always a possibility that someone has used this trick to listen in on you either on purpose or accidentally. This only effects Facetime users communicating with other Facetime users. And Facetime is only available on Apple products.