The contact owns a 2025 Toyota 4Runner. The contact stated while reversing at an undisclosed speed, there was an abnormal sound while the brake pedal was depressed, and the vehicle shuddered. No warning lights were illuminated. The failure had occurred on several occasions. The vehicle was taken to a dealer to be diagnosed; however, the cause of the failure was not yet determined. The dealer made the contact aware that the failure was a known issue. The vehicle was not diagnosed or repaired. The vehicle was taken to another dealer, Servco Toyota Honolulu (2850 Pukoloa St #200, Honolulu, HI 96819); to be diagnosed; however, the cause of the failure was not yet determined. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was approximately 5.