https://www.bleepingcomputer.com/news/security/apple-releases-fix-for-group-facetime-snooping-bug-in-ios-and-macos/

Apple has released security updates for iOS and macOS that fix a severe bug in FaceTime that allowed callers to listen in, and potentially view, the people they were calling without the call being answered.

At the end of January, videos started circulating on social media about a serious bug in iOS and macOS that allowed users to initiate a Group FaceTime call and listen in on those they were calling without that person answering the call or even knowing that their microphone was activated. To make matters worse, if the person receiving the call pressed the power button to mute the ringing, their front-facing camera would turn on allowing the caller to see what was happening in the room.