By what I’ve read/remember (grain of salt and all), all or almost all parchment papers use silicone these days, but PFAS parchment used to be a thing.

Edit: Wikipedia says:

To get its non-stick properties, baking paper is either treated with a “quilon" (a solution of chromium(iii) in an acidic alcohol to modify the cellulose) or cellulose coated with silicone.