Unfortunately, it’s definitely little scratches rather than extra metal on there .. Apple support are saying the warranty doesn‘t cover ‘normal wear and tear’ .. I did say that it’s not had any ‘normal wear and tear’ I’m in lockdown lolI thought the back was fairly resilient and can only be marked by materials that are harder than the glass. Do you think that the magnetic back is picking up pieces of metal and that is causing the issue when its in your pocket. I would imagine that the other colour phones will have the same issue