# Can the ancilla for Qiskit's mcx with mode="recursion" be dirty?

I think their implementation is close to the one from here which does use a dirty ancilla, but I just want to make sure

I would be inclined to say no, since Qiskit code itself seems to append pre and post-gate instruction chain of gates in case dirty_ancilla is passed to the chain MCX which is not the case for recursive MCX