I agree rust/corrosion.
“At time of the inspection there was some rusting and or corrosion observed within the electrical (service or distribution) panel on one or more of the electrical circuit breaker connection terminals. This condition could cause poor contact at the connection terminal and the potential for overheating. For reasons of health and safety this inspector recommends further evaluation by a qualified licensed electrical contractor and for any corrective repairs that may be necessary in accordance with accepted practice.”
Great response. Thank you!