Brown "kraft" paper, is there a kashrus or Passover concern?
Brown "kraft" paper is commonly used by restaurants, caterers, food service to put hot & or greasy food directly on the paper. Many of the manufacturers may use "recycled" material from unknown sources.
Pesach raises additional concerns, starchs. There may be upto 5% starch in some of them. the source of the starch may be chometz, kitinious (legumes) or anything else.