You can do this with brown paper lunch bags. Put some popcorn in a bag, fold the top so that it doesn't open when it expands, and hit the popcorn button.
That article appears to be talking about the type of bags and wrappers you get from fast food joints. I don't think a standard "brown paper bag" contains PFAS.
I think that only applies to variations of “non stick” or grease repellant paper bags, which is often used by fast food joints to avoid the food sticking to the paper.