This is very common with Paint Protection Film of all brands. It is related to the difference in the refractive index between the PPF and the paint/clearcoat on the car. It is most noticeable on compound curves because the film needs to be stretched over these areas to allow it to be installed without wrinkles. When the film is stretched, it becomes slightly thinner in those areas which cause the phenomenon seen through polarized glasses.
It can also occur on flat surfaces when the installer needs to use a drying solution (as opposed to a slip solution) such as alcohol and water to get the needed bond to the paint. This is due to the difference in viscosity of the fluids and their effect on the adhesive’s properties.
Polarized glasses have this effect on several different multi-layer surfaces (not just paint protection film) made of glass or plastics.