I've wondered how hard it is to detect on a craft like that. There would have to be some separation or delamination prior to the entire tail section jettisoning from the aircraft. I don't know if this was something visible from the external of the aircraft, internally, or not at all. It appeared to separate where the vertical stabilizer met the fuselage.
I'm always concerned about structural integrity where the wings meet the fuselage, to see the tail come off in that manner is quite shocking. It appeared to separate after the corkscrew maneuver, possibly residual fatigue induced from the other aerobatic maneuvers that preceded that one.