@moira It's not uncommon to find chromed bearing surfaces in really cheap old hubs, and that will tend to flake off. They just chrome the entire hub shell. Nothing much you can do about it other than clean it up and install new bearings.
Former bicycle mechanic, retired tech worker, repairer of things. Tell me about your bike and I'll try to help you fix it. 🌉 bridged from ⁂ social.coop/@pws, follow @ap.brid.gy to interact