>>9871338You need to paint it over, not polish it. I bought it in 2019 according to my old pics. It happens when the paint has bad coverage, and since these silver parts are clear-paint-over-bare-diecast, you can't really tell how well they are coated.
With colored paint it's less of an issue. Out of the four removable turrets here only one has some visible oxidation.
>just a bad batchThis isn't a batch-issue but a random, "factory-worker having a bad day" issue.