This is a picture of a roof leak of a roof penetration. The component is a service entrance mast pole. The water intrusion is evident. It could or may have already caused a mold growth oportunity. A tape sample test can be performed to determine if mold is present.
Mold or not, that roof sheathing has been or is being damaged by moisture and is beginning to deteriorate. I would say something along those lines and recommend replacement or at a minimum careful monitoring for inevitable replacement.