>>3738735that is film grain (not sure if real or added in post)
the way color film works is that theres a bunch of different crystals that are sensitive to different colors of light scattered on the surface. the amount of crystals for a given color in any region are so dense that when you expose it an image it just looks like the image. some crystals happen to get hit with more light than others, or are just more sensitive than others hence the speckles.