I got my scans back from the laboratory and you can see that the sky looks like and oil painting for some reason that I don't know. Can you guys tell me if this is because some lens issue ( vivitar 28mm 2.8), the camera(canon ae1-program) or the film(portra 400). Some other photos have this effect but only visible on the sky.
https://imgur.com/a/LKkLDnH
https://imgur.com/a/LKkLDnH