Laptop oxidation stains or something else?

So I'm selling my laptop and today I took off the stickers and cleaned all the sticky stuff off. After I got it all there's an insanely distinct "stain" from one of my stickers. All the other ones have faint "stains" on them but this looks really bad. I looked at previous posts and people said it was oxidation but none of my other stickers show this much staining. Does anyone know how I could get rid of this today since I'm shipping it tomorrow?

Before and after photo: https://imgur.com/a/N5jnzOB