The contact owns a 2024 Tesla Cybertruck. The contact stated that while waiting at a railroad track with the Full Self-Driving (FSD) feature activated, the destination was entered, and the railroad lights and gate were lowered when suddenly the Full Self-Driving (FSD) disengaged independently. The traffic light turned green, and the driver was required to take control of the vehicle. During the independent disengagement of the Full Self-Driving (FSD) feature, the vehicle abruptly accelerated. The contact was concerned that the failure might have result in a crash, had he not taken control of the vehicle. The contact stated that he submitted a report through the vehicle App. The vehicle was not taken to the dealer to be diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 3,400.