Hi,
I don't see difference of color between the fin and the blotches on the horizontal plans. If the fin is white, other parts of the tail have to.
The plane of the photo below seems identical to the shots above, but the number doesn't seem 21 but 13 or something similar; this similarity is strange, they have even the same (supposed) eagle emblem on the nose.
Other tails... I think to see one on the first shot and on the background of the photo below, they seem light too.
So it seems that some (or all) the planes of the unit had white (or grey, or light blue) areas appearing as a winter camouflage.
Regards
Massimo