The fact that it's a giant? The big machete? The crown?
Also, tell that skeleton bit to Darkbeast Paarl.
Except the crown looks nothing like Yhorm's, neither does the weapon. He looks more like a skeleton lord from DkS2. And Paarl is one skeleton, Bloodborne is certainly not known for its skeletons, so redesigning Yhorm to fit BB's themes wouldn't have any reason to make him a skeleton.
There's no reason to assume this is specifically supposed to be Yhorm just because it's a giant with a sword if the artist didn't say that's who it was.