looks like the the epoxy resin didnt set properly.
try polishing it
if that is the case of epoxy, then there is no way to solve the prob....as the epoxy is already hardened.
I hope the blemish on the cf is just surface blemish....which can be polished off.
How come the problem wasnt spotted during the buying the spoiler?
polish
Due to our hot and pouring weather, it is always advisable to get it coated as the lacquer layer in carbon fiber is thinner than in conventional paint. In your case, first polish it then do a coating thereafter. I did on mine, so far still looking good as new.