(HELP) wheel polish gone wrong

[Ctyler93]

I noticed some black stains/marks on all 4 rims of my girlfriends 4Runner. I scrubbed with wheel & all purpose cleaner which didn’t do anything so I tried some polish and a microfiber applicator pad. I went after the largest black spot only to reveal what you can see in the photo, a more flat/raw looking alloy. My first thought was I had got down to the metal/base coat but what was even more strange is I noticed wherever my pad made contact with an area that wasn’t a black mark instantly became black with just a few rubs.. as if there was a ridiculously thin clear coat.. over grey paint, over black, over grey! I know it’s unlikely to have been painted 3 times but it is an older truck. Hopefully someone can shed some light on this.