I have the same problem, the lens cover on my iphone 7 has broken - this has been in a protective case since purchasing and also has a tempered glass screen protector on it, no scratches or marks on the phone and has not been dropped - just been on to Apple Support who have advised taking it into store , I will let you know what they say - but will not be happy if I need to pay for this. My phone provider has advised me this is part of the warranty but I seriously think I will be told otherwise to try and get money out of me.