I mentioned bluing a CZ-75 (not B) elsewhere on this forum.
I tried several things to get the polycoat off. One of the things I tried was aerosol brake cleaner. Didn't take it off, but definitely DID dull the finish. Sounds like someone tried cleaning yours with GunScrubber or Brake Cleaner/Carb Cleaner.
As someone else suggested: see if can find some plastic polish. (Maybe the stuff they use to clean/polish fibreglas. Or, more simply, car wax. It maybe needs a coating of wax to return the shine...)