FaceTime launches on my Macbook when I have incoming phone calls, even though I'm not logged into iCloud I have an iPhone and a work Macbook.  Despite not being logged into iCloud with FaceTime, whenever I get a call on my phone, FaceTime launches on my macbook.

I've tried logging into FaceTime, disabling wifi calling and then logging back out. Still happens.

Interestingly, there's no way to answer the incoming call.  FaceTime launches in a logged out state.
Disable Calls on nearby devices on iPhone too. Settings > phone > Calls on nearby devices.