Free(with ads) on demand not free

Most of the movies that are listed in my free movies on demand (the ones that are free with ads), are NOT free! I can see the premium movies costing money, but these are listed in the free section! Almost every one I click on say available to rent or buy. I don’t understand why it’s doing that! It’s never done that to me before! Is Comcast/Xfinity having some sort of glitch?