On Jan. 1, 2024 at around 2:19-2:20PM, the vehicle in front of me made a sudden brake causing my vehicle to trigger the Automatic Emergency Brake. My foot was on the brake pedal as well, I even floored the pedal to make my car stop right away but it continued anyway, the pedal felt so loose/soft. My car almost made a full stop but when the vehicle in front of me started moving, the car started to somehow accelerate, I was confused as to why the car was moving when my foot was firmly pushing the brake. This unexpected move caused me to rear-end the vehicle in front when they abruptly stopped for the second time. My thought is since the car in front moved, the Tesla thought the vehicle in front was no longer a threat and stopped applying the brake to make a full stop. I watched a lot of AEB videos online. 1. Automatic Emergency Brake - malfunctioned, maybe, the car log has it but I took a photo that AEB was in progress during the incident 2. My experience is similar to a car without a brake - no matter how hard I pushed the brake pedal, the car didn't stop. It's frightening because I'm out of control over the situation. 3/4. My car was already repaired but I haven't taken it to a Tesla Service Center to inspect the system - the manual brake is working though 5. There were chimes and screen notifications that an Automatic Emergency Brake was in progress. I can upload the dashcam recording if you need it.