It looks like corrosion caused by bad prep. Had it on the hood of both my 2012 Mustang GT and my 2015 Explorer sport. Both of them were covered under warranty and both received new hoods.(coincidentally both were black)
Had my drivers side replaced not long ago, they told me the axle assembly was the only option. They told me Ford does not make a repair kit for our axles, not sure what your dealer is looking at.