A major FaceTime bug that is publicly broadcasting on the social media right now, which allows you connect to someone and hear their audio without the person even accepting the call, and raising up a huge privacy concern because you can force a FaceTime call with someone and listen to what they are saying, maybe even without being noticed by them.
To take advantage of the bug, all you have to do is add your phone number to your already started FaceTime call, then you will found that you have begun a group FaceTime call including yourself and the audio of the person you originally called, though they haven't accepted the call, which obviously creates a major FaceTime problem.
There appears to be no way to avoid this bug other than completely disable FaceTime on iOS and macOS, and Apple has said the issue will be fixed in a software update later in the week, in a statement to Axios: "We’re aware of this issue and we have identified a fix that will be released in a software update later this week."
For now, you can either delete the FaceTime app or just disable the feature completely under the Settings - FaceTime.
Update: Apple disabled Group FaceTime feature for now
Update: Apple disabled Group FaceTime feature for now