FaceTime Bug? Devices used iPhone 15 & Macbook 2019

This just happened to me and my best friend (8-6-24 a little bit before midnight). We were in a group call earlier, but I left that and made a new one with just me and her. All of the sudden I hear loud static and I tell her that I am lowering my volume, because for whatever reason it sounds like she is washing her phone in the shower. I am on my MacBook, so I did not have FaceTime open directly to see what was happening. She heard the same thing too, but it was not her. She was trying to tell me, but I could not hear her. All I can hear is loud static. She then heard someone say "whats good [her name]" in a really deep voice. She got spooked and hung up the phone. On my end, I heard loud static and mentioned the shower thing and it was still loud static. Not too long after, the call dropped. In reality, she hung up the phone, because she heard someone say her name. But we were both on the same FaceTime call and all I heard was static and no voice. No one on our call logs appeared to have joined the call. She then called back and told me what happened. I did not hear the person say that, but we both heard the loud fan noise. So that bears the question as to what happened? Did her phone call someone by itself? She has an iPhone 15 btw. I read other posts from the past on the internet where similar things happened to people either on FaceTime or a normal call. I am American, she is Canadian. I do not know if an international call has something to do with it or what. This never happened to us before.

This is just weird and creeps me out. Imagine someone joins your FaceTime call. You have no idea, because nothing pops up on either parties end. They can hear everything that is going on. You have NO IDEA there is another person on the call.