The contact owns a 2019 BMW 330I. The contact stated while driving at approximately 35 MPH, the brake pedal was depressed and there was an abnormal sound. The contact stated that while the brake pedal was depressed, the brakes failed to engage as designed. No warning light was illuminated; however, the ‘Electronic Stability Control System Malfunctioning’ message was displayed on the instrument panel. The vehicle was taken to a dealer to be diagnosed; however, the cause of the failure was not yet determined. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was unknown.