I've find searching for care/correction information on PPF to be a lot like leather care! There is tons of conflicting information out there and it's annoying!
Over time the film will accumulate marring just like paint and we need a way to correct it. Most 3M installers say to use IPA to remove marring but IME that is ineffective and I find it funny that the film comes marred up right from the installers. If IPA works so well than why are they delivering a new wrap to the client all marred up?
I've been polishing PPF since the mid 90's and I've only run across a few that have given me trouble. Is polishing bad for the film? I have no idea. I do know that the films have always left my shop looking better than when they came in and without polishing them they were never going to look as good as I made them. Until one of the manufactures steps up and shows us an approved method for correction of film I'm going to continue doing what works for me.
I tend to reach for Menzerna polishes...FPII is what I like to start with.
Here is a 50/50 on 3M film
The new Ultimate "self healing film" by Xpel looked to be very promising when I was at SEMA and the installers I know are loving it as well.