I'd assume because it stalled in overspeed condition. Caution advised, it is a SIM not a plane, still it looks controllable, but without seeing the pilot's commands dangerous to draw conclusions.
Proffesional observation at 1:33
Samolot uratuje sie sam, beleby mu pilot nie przeskadzal
The aircraft will guard/safely take care of itself, if it was not for the pilot standing in the way.