The real reason Art looks different in the 3rd film is because for Terrifier 1 and Terrifier 2 the molds they applied to David’s face were molds made from OG art actor Mike Giannelli, it wasn’t until T3 that new molds were made from David’s face to allow him to be more expressive
i just had an autism explanation about why art looks different in the third movie cause the person behind us in the theater said they didn’t like how they changed actors for the third movie.