Vintage Coach pink trench coat size 12 in need of some love

This beautiful vintage light pink Coach size 12 long trench coat with bright magenta pink leather trim, silver colored hardware, and a white lining with colorful polka dots that needs a fabric restoration. One day I went to take it out of the closet and it has what I can only describe as a rusty patina on it. I don’t know what caused it, but I’m sure someone with more knowledge and skills than me can figure out a way to restore it. Sold as is.