It always happen when owner install with low grade windows film especially those infra red film.
Well back to your question, its always 50% vs 50% chances. There are 2 process might cause the
demister line to peel off from rear windscreen.

1. During the removal.
2. After removal, the cleaning process with shampoo.

Anyways, if you have cover with insurance then it should be ok to replace the rear windscreen in case
the demister is spoiled. Do PM me if you want to know more details.