Apple iPhone XS “sapphire” camera lense covers break spontaneously

My 3 month old iPhone has always been in a military grade case. It hasn’t been dropped or suffered impact in any way. The “sapphire” glass lense covering the camera somehow cracked and eventually broke. I went to iStore in South Africa and they wouldn’t replace the unit for me. 1 - sapphire shouldn’t break in the first place (especially if it hasn’t suffered an impact) 2- I have seen several similar complaints from all over the world where the lense cover breaks for no reason - this leaves me to believe that there was a problem with the build quality (some common production error) I think it’s really shocking that Apple claims that the glass is sapphire but won’t cover it in the warranty when it breaks for no apparent reason. When paying R26 000 for a smartphone I would expect better service. Instead they want to cash in on it and replace the entire double camera module at a rediculous price. This is such a let dissapointment - the customer service used to be the best out of all the giants.