It’s maybe not a filter as such, but the image has been “softened”, or had “noise reduction”, the skin texture has been reduced, you can see it more clearly on the skin area of her neck and chest, where softening/reducing definition/noise reduction has blurred out the natural texture. It’s not an old phone or just blurry, the photo has been enhanced. Very easily done on most phones.
anyone who has done it, which is a lot of people. Can see it immediately. It’s incredibly obvious.