LE MANS 1955 : the unauthorized investigation

On June 11th, 1955 at 6:28 p.m., the legendary 24Hrs of Le Mans race turned into a nightmare and became the deadliest in the history of motor sport. The Mercedes car n°20, driven by the Frenchman Pierre Levegh, collided with an Austin Healey before taking off in the crowded stands of the circuit. Official report: 82 dead and more than 120 injured. Despite this accident, the race continued, without the German team which deserted Le Mans overnight after withdrawing and ended the next day with the bitter victory of Jaguar.
Today, 65 years after the tragedy, numerous questions remain despite investigation, but one remains more important: why would the files be classified and sealed until 2031 when they should have been made public a long time ago?