Component or System That Failed: The rear passenger seatbelt on the right side of a 2021 Lexus RX 450h malfunctioned during a collision. It is still in the vehicle, which is available for inspection upon request. How Safety Was Put at Risk: The seatbelt failed to restrain my son, who was seated in a booster seat and weighs approximately 78 lbs. During the collision, he flew forward and struck the front passenger seat and center console with his chest and upper abdomen. This malfunction could have caused severe injuries, and while his injuries appear minor, it posed a significant risk to his safety. Problem Reproduced or Confirmed: The seatbeltâs failure has not been reproduced or confirmed by a dealer or independent service center. However, the seatbelt remains fully extended and does not retract, indicating a potential defect. Inspections Conducted: The issue has not yet been inspected by the manufacturer or a service center. Police were present at the accident scene but did not specifically inspect the seatbelt. Warning Lamps or Messages: No warning lamps, messages, or other symptoms indicated a problem with the seatbelt prior to the collision. Best Assessment: Based on observations and my sonâs account of the incident, it appears the seatbelt retractor mechanism failed to lock during the collision, which is a critical safety feature. I am submitting this report to ensure the potential defect is investigated to prevent similar occurrences in other vehicles.