Are custom skins a bannable offence

The T&Cs say mods that give you an advantage or inputs are will result in a ban, and I understand this. But custom skins give no advantage and are purely cosmetic. (All the officially released skins I buy this isnt to emulate a skin sold by RIOT Via the store for RP) Things like Dark star orianna or Surprise party Rengar. Things not sold but fans have taken it upon themself to make
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