False! According to 3M Company, which holds the original patent to window film dating back to 1966, film does not cause seal failure:
“We’ve been applying 3M Window Films to insulated windows for over 40 years, having seen several millions of square feet of film applied to date.
When recommended films are applied to the inside pane of an insulated glass unit, there will be some absorption (except with clear safety films) of the sun’s energy, which will increase the temperature of the glass pane. Some of this heat will transmit to the airspace, slightly raising the airspace temperature. However, even a 20 F degree increase (unusual for most films) will result in a less than 3% change in air pressure. Properly made windows are designed and tested to withstand 22% changes in air pressure.
Risk of seal failure is determined largely by the quality of workmanship and the quality of the materials that go into building the insulated glass units. The best guard against seal failure is to purchase well-made windows from reputable manufacturers that have solid experience and histories with insulated windows.”
Respectable manufacturers provide consumers reassurance by warrantying against seal failure due to the installation of window film.