Yellow car owner here too (not a SEAT though) and it's a big issue for me as the car has had some paint work before as well.
The
problem with yellow is that the pigment in the colour is what fades. The pigment breaks down and then changes colour.
Now this isn't too much of a
problem if your car has single stage paint, without a clear lacquer on top, as you can hand or machine polish the paint to remove the oxidised, damaged layer. Colour and gloss could be restored.
If however, like most modern cars you have clear over base paint, which ovni and chrono yellow are as far as I am aware, then it's a big issue. The fade is still in the pigment, in the colour coat, but you cannot polish the colour coat to remove the dead paint becuase it's locked away by the clear top coat. Sure if it's just the clear coat that has oxidised and looks a bit faded and milky, a hand or machine polish will sort it out, but if like me and most yellow car owners it's in the color coat theres not much you can do other than live with it or have it painted.
![Crying :cry: :cry:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)