Many aircraft have been produced with 2mm thick polycarbonate material windscreens. From my observed experience, fuel spills while decanting fuel over the wing, wind wipping up fuel to spill on the windscreen has been the cause of most if not all windscreen crazing/cracking. Its was a big problem in NZ.
Jon Farmer did an analysis on this and observed this problem, even vapour can cause problems, I have personally witnessed a pilot tipping fuel from a 20 LTR container into the overhead fuel tank filler neck and seen a gust of wind splash a small amount of fuel onto the windscreen. Instantly the windscreen crazed. There have been the odd cases of pilots doing Aerobaties in a non Aerobatic Aerocraft and signficanly exceeding VNE. In Australia this was proven by the flight data recording downloaded from the dynon skyview unit.
In one case after an accident the pilot In command said a drone hit his aircraft and smashed in the windscreen in flight. The aircraft crash landed in a paddock literally out of control. The NZ CAA said it was sunlight damage/discolouration, that caused the windscreen to break up in flight, despite being told the aircraft had been hangered all its life.
The first person on the scene after the accident (other then the PIC and his Pax) was a very experienced engineer having been to many aircraft accidents to retrieve them and was able to work out what most likely went wrong. One fuel tank was empty with that fuel selector on. The other still had 35 Ltrs of fuel and that fuel tank selector was off. I don’t like to speculate, but its not difficult to work out what was the most likely cause of the accident (see my previous article on fuel management). I immediatly imported, 8 new 3mm thick arcrylic windscreens.
That were presold and all new aircraft have this type of wind screen fitted since 2019, hopefully this is the solution.