Ah, now that takes me back to battle school. One fellow in my section did that, it stripped the upper receiver group of his C7A1 back to white aluminium in a few very noticeable places. The thing looked like a Dalmatian, the panic that resulted!
I crafted the genius barracks fix, a "Magnum 44" black marker, every morning, just before inspection he would colour in the splotches carefully blending into the other non-ruined parts of the finish.
We were successful with this until the final weeks of course, when one Sergeant noticed his work, the fellow said it has been like that since issue and he was just trying to make it more presentable for inspections. The entire section nodded in agreement to support the lie, the Sergeant accepted this, told him not to bother any longer as the weapons techs would fix it, and told him good effort for making his kit look good.
To close, oven cleaner is a bad product for firearms finishes, including anodizing.