[The ruling on an agent borrowing zakat or expiation funds]

Answer: If a man is an agent over zakat or expiation, it is not permissible for him to consume it and then replace it—unless he has been authorized to dispose of it. This is the meaning of their statement: “except if he is mufawwaḍ (explicitly empowered).” If he borrows from it without being empowered to dispose of it, then he must replace it, and then seek authorization from the zakat-payer to disburse it.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1