This happened to me earlier this year only with a Volvo, and I was the pedestrian. I was standing on a corner, on the verge of a country road holding a mechanical strimmer waiting for the Volvo followed by an Audi, to pass. I had seen the Vovlo and the driver had seen me. The Volvo then stopped abruptly and the driver didn't appear to know what was going on. Fortunately the Audi Q7 (following way too closely - as Audi Q7s are almost invariably known to do) managed not to drive into the back of it! As the Volvo had no reason whatever to stop and the driver didn't seem to know why it had stopped, my assumption was that this was a Forward Collision Mitigation system decision, not the driver's.
What a stupid and dangerous piece of technology! It's hard to believe that car manufacturers are using it when it's clearly not 100% foolproof. I think you might want to disable it for your own piece of mind. I'm not at all sure as a driver that I have any intention of hitting any pedestrians anyway - a bit like the technology that prevents tailgating, I'm as capable of not tailgating now as I always have been. It's a bit of a worry to think that car driver's should need technology that prevents them from driving into the back of the car in front or hitting pedestians - shouldn't we be able to manage this ourselves? Actually, thinking about it quite a lot of driver's clearly can't.