I was wondering the same thing about the scales.I agree, very mild frostbite. Or somehow the circulation was cut off. I wouldn't bother messing with it, if they were mine.
Mine do occasionally get mud balls caked around their nails, from scratching damp soil, then walking in the dry stuff, and it hardens rock solid. I have to take pliers to break the chunks off! If I miss any, they can build up and cut off the circulation. I had some lav orps that a broody hatched, and I couldn't get near the chicks, and this happened to a couple of them. Looked a lot like your picture (after I broke the mud off)
Also, can't tell for sure in the pic, but are the scales raised any? Just make sure there aren't any scaly mites up in there.