Technically speaking, I think the term "mark up" is a bit misleading and maybe a better term would be commission or fee. That is what you are getting.
The price you get is not really a true mark up. You are charging FAA a fee for using your image, to be sold to the end buyer. They sell the image and pay you your fee plus 5% of the selling price of any framing or any product that the buyer buys. Then you are out of the transaction. Unless there is a return of course. On the returns, you are debited for the amount of the fee you recieved, but FAA eats all of the other cost of doing the transaction. THAT is a great deal for the selling artist.
That fee is not really a mark-up. You as the seller has no other participation in the sale or the of the cost of goods that go into the finished product, including the shipping. You do not chose them and you do not pay for any part of them.
FAA handles all of those other functions and the is no reason what so ever to give disclosure on something that the selling artist has no participation in.