Sounds fishy to me with same coat on hull and cushions.... I use different wax for the hull compared to vinyl protector....
Anyhow, I have seen some horror examples of ceramic coating on a few year old boats here in South FL. I watched one being sanded down to get it off and rebuffed and waxed to look like new. I am sure it also has to do how the oat is stored, indoors under cover or outside. The darker the hull color the more critical it becomes to frequently clean and wax the boat, the ceramic in this case did the situation worse as you are supposed to do nothing to maintain it for years.
I am storing boat indoors and rinse and clean after each use and have it waxed Ab. once a year.
I am using a self administered ceramic on my cars, they are garaged and it works really well. Easy to just rinse and dry instead of having a heavy wash ever so often. I don't take them to car wash so that is maybe another difference.
So make sure you watch the coating for deterioration or dulling the surface at any time but getting rid of it is a b__ch.
Good luck
H