Oh man, the ossified window tints trigger such PTSD for me...
Every car I've pulled tint off has had the layer separation, even a 2007 golf I did in 2022ish. But by far the worst was the hatch on my RX7: as if lying on my back in the boot to work overhead wasn't bad enough, Mazda applied a factory tint, then the demister strips. Then some racerboy slapped a 20%vlt film over that. Both the aftermarket and factory tint layers are so brittle they peel in 2-6mm long fangs at best. The demister strips are less than a razor width apart, and windex etc. fogs the factory tint, but nothing softens it. So now I have plain glass strips with ragged edges I still need to clean up of purple/grey/frosted mottle along the heater lines (which are orange).
I can sort of see well enough to reverse it, but it's pretty galling to look at/through...
So Bryce you *definitely* dodged a bullet with your rear window replacement...