Until now, 12/11/2025, the uncorroborated root cause of the glass's spontaneous failure. At one time, it was attributed to aftermarket suspension upgrades stiffening the suspension, transmitting greater twisting and vibration to the unibody, which uses the glass as a structural component.
A quote from Rennlister Artefact (Charles):
"It happened at the end of crossing a mile-long metal bridge, producing tons of vibration in the car. I doubt it's a coincidence."
Another uncorroborated root cause is localized glass heating from a failing glass electrical connection to the glass heating feature or the high-mounted stop light.
In any event, consider this procedure once the new glass is installed to eliminate corrosion issues around the glass going forward.
https://993servicerepair.blogspot.com/2020/09/avoiding-known-problem-with-corrosion.html
Also, here is a page that discusses water leaks:
https://993servicerepair.blogspot.com/2021/08/wet-floors-in-your-993-and-how-to-dry.html
Andy
