Gel coat is the final finish surface for a fiberglass item. So, the answer is Both.
"Gelcoat or 'Gel Coat' is a material used to provide a high-quality finish on the visible surface of a fibre-reinforced composite. The most common gelcoats are thermosetting polymers based on epoxy or unsaturated polyester resin chemistry. Gelcoats are modified resins which are applied to moulds in the liquid state".
So, if the oxidation is too bad you can use a "cleaner/wax" like this by Meguiars. https://www.amazon.com/Meguiars-M501.../dp/B0000AXMY8