In my case, FSD drove a little TOO carefully. I got rear ended this weekend, while waiting for FSD 12.3.4 to decide (in its hesitating, on again off again way) to make a right turn into traffic. The car behind me probably saw my car pull partially into traffic (which it did), then slow/stop (which it did) because of cars in the next lane (not the lane I was entering). My best guess is, the other driver likely looked left for incoming cars as they accelerated right into my back bumper, on the assumption that I was still in motion. Ouch. Will need a new liftgate and new plastic bumper - it's broken and I can see the big square looking metal pipe thing underneath that presumably actually absorbs the bigger shocks. (Low speed: no injuries at all thankfully).
FSD is really safe, but the over-abundance of caution is unnatural (to all but Driving School students) and can cause problems.
And before naysayers chime in: Yes, I am responsible for the behavior of the car during FSD, and I was paying attention and very on edge about its indecisive behavior. I had already goosed the accelerator once earlier on that drive, due to impatience in entering a clear lane that had partial view obstruction. And yes, the person behind me, by accelerating without looking, is responsible for rear-ending me. So in terms of actual responsibility, it lies with the humans. I want to also make the point, made to me very clearly this weekend, that indecision shown by FSD at times can also be unsafe.
I am not sure if the hit itself disengaged FSD, or if my likely reaction of hitting the brake disengaged it, but I can at least hope my chagrin (my beautiful Y is now no longer pristine) and hassle gave Tesla at least one useful data point.
Yes, still a fan of FSD, but I will choose much more carefully when I engage it. It had given me a great 10 mile drive on Friday, and I was feeling confident in it from that, but my Saturday was ... not so joyous. I'm hoping my beloved blue dragon will be healed soon.