I had one last fall, San Jose to Las Vega. There was heavy traffic around La (surprise surprise) so we were probably only going ~30? Anyway car jammed on the brakes when there was plenty of room in front, alarming to say the least. Driver behind was not impressed with his perception of me brake checking him
No sounds or anything that I recall, no dash cam for me at that time either. I did call service within a minute or 2 of the event, hoping for logs or something useful. After many questions about milage since last firmware update etc they scheduled a camera calibration visit but at the visit about 10days later, the techs/service writer said it's beta software and sent me on my way .. luckily it has not happened since though plenty of phantom braking with AP but I pretty much don't use that anymore because of it, not even cruise because it (traffic aware cruise) suffers that same overly aggressive caution...