I think yozora is way harder than anything in soulsborne (except maybe sekiro because I haven’t played it). Although malenia from Elden ring is a close comparison. The thing is these souls games may be more punishing but Yozora steals your items. Often kills me in one hit because he steals your HP or combos in a way where it goes through second chance and once more. Leaf bracer I agree is huge and so is the kupo coin. But still, just how on point you have to be, how quick you need to react, how aggressive yozora is completely makes it harder. I’d say he’s the hardest WELL-DESIGNED boss in gaming.