From my observation this was…
From my observation this was not a vinyl wrap but was vinyl lettering only. I am a signmaker and do installation and removal of vinyl lettering on boats, trucks, trailers and various other vehicles. What has probably happened is that the area covered by the vinyl has been protected while the uncovered area is exposed to the elements of rain, sun, dirt etc. which usually leaves a shadow effect. Sometimes with boats and factory original painted vehicles compounding may help removing the ghosted shadow effect.
I operate a mobile sign shop that is in a custom built trailer that has a polished stainless steel skin. I have removed some of the lettering from the stainless steel and the results have been the same. I have also encountered discoloration and acid rain oxidation on the stainless steel. My trailer was built in 2006 so I don't expect it to maintain the original appearance but I have used a product called "Whink - Rust & Stain Remover" that has helped remove some of the oxidation. It is recommended to test a small area first to be sure it does not damage the surface.
Please feel free to reach out to me through my email on my website:
www.RIWraps.com
Timothy Tibbetts