FAA Order 8130.34D — UAS Operating Limitation A-25
Appendix A · p. A-5
This UA is prohibited from flight with any externally mounted equipment unless the equipment is mounted in a manner that will prevent in-flight jettison or detachment. Installation of external stores (pylon and equipment) or external fuel tanks not approved by the manufacturer or the original military operator is prohibited. No change in external loading for the aircraft (for example, a change in pylon, rack, or external store) from configurations approved by the manufacturer or original military operator is allowed, except to prevent jettison or detachment.
This limitation is only for former military aircraft.
Verify it yourself: the eyeball above opens the exact page of Order 8130.34D with this limitation highlighted.