I was playing with my chickens today, something I hardly ever have the time to do it seems, and I realized Mantis has teeny tiny feathers between her toes! WHY?
Those are called "stubs" and would be a disqualification for her at a show. Generally they can pop up after bathing a chicken in preparation for showing, when the skin is soft. Most exhibitors will carefully inspect the legs of clean-legged birds before putting them into a show cage.
It is preferred that you do NOT pluck it out for show, but some people do. I've never heard of it in Polish though, and no, no feather-legged breeds back there for at least 100+ years.
It might just be a fluke, or it might be that the hatchery accidentally or purposefully threw in a feather-legged bird a few generations back.