Lotsa good theories going around, but I've been painting and vinyl decorating
windows for a lon-n-n-ng time and never had one break from painting or vinyl coverage.
Even with gilding
windows with black japan paint with varnish doesn't do it to very large areas. With today's gold leaf vinyls, I can't tell you how many
windows we've done with whole black vinyl areas over top of gold leaf vinyl.
Yes, there are some instances when this might pop a window, but I think that's some manufacturer's way of getting out of stupid accidents like this one and blaming application failure.
I would venture to say, your vinyl had nothing to do with it breaking. Probably a competitor or some pissed off customer who didn't like the 'Attitude' their hairdresser gave them and threw a rock at the window.