The change on the statues illustrated above is especially interesting when inspected closely.
They bore large covers on their backs to ensure they would not become seedbeds for spreading darkness.
As written on the Cleric Robe and these large turtle-looking covers are also visible on the pilgrims from the cinematic as well as from Yoel and the others' corpses the player sees scattered around the High Wall of Lothric.
On the first statue, it seems that a corruption begins on the back, and as it spreads over the body, the host body grows wings. While this type of corruption seems to also start from the back, it seems that it is not the same as the ones seen on Iudex Gundyr and the Pus of Man. The latter type seems to be an imperfect mutation, as it ends looking like a black serpent with a huge clawed hand, but the statues with the wings seem to resemble dragons. As mentioned earlier on many occasions as a recurring theory, serpents are viewed as imperfect dragons. Knowing Oceiros experimented in creating dragons and humanity, it is safe to speculate that this corruption is his work or his work went wrong.