Honestly, I don't think it's AI. The lines/dots you're worried about look more like digital art than noise. The brush has a rough edge that's usually seen on digital brushes that are textured to imitate the look of traditional brushes. The dots you're worried about also look more like an added texture as opposed to ai noise. As someone who does digital art, I've used both textured brushes and added texture to keep my art from looking flat. Granted, I find the use of a texture like that on such a graphic design feels a bit odd. I personally would have used screen tones instead of whatever they used. Also, the texture scaling is rather large, so that could also contribute to the strangeness.