It’s a very common issue and usually just cosmetic.

It is often caused by the scuttle being steel and the quarter panel being Aluminium.

I think some years of Morgan’s are more prone. My Dad had a 2007 car and that had corrosion but I have seen other cars that are unaffected

BHM have one for sale for a good price given the paint issues

https://morgan-kent.com/2007-morgan-4-4-1-8-duratec-engine-28000-miles/

The key point is that it’s cosmetic and won’t impact the way it drives. However it will impact the value.