How to determine if the shiny metal frame in my iPhone replacement is a defect?

My original phone got stolen back on April 9th in Primark in Marble Arch London and I got a replacement through AppleCare Insurance Theft and Lost. This was the device they sent me and I noticed while I was cleaning it that there is a bit of a shiny bit of gold metal between the ear speaker and frame of the phone where is has been circled. It doesn't really effect the functionality of the phone during phone calls or anything but it really bothers me especially when I am looking at it through the glace of the light.

As I remember my last 13 pro max that I originally had that got stolen from me don't think had this and I have been to several apple stores showing them this issue and they don't seem to think that it's a fault as much and have done serval dragonises test on it and have not found on fault on it.

I even had a express replacement on the device which even had the same metal defect on it and was in much worse condition then this phone with cosmetic damaged, a misaligned USB port and lose silent button. So I sent it back to apple and ended up keeping this one but somehow I feel it is not normal and now the serial number and AppleCare coverage is invalid on this device now so not much can be done about it right now although the customer relations team is suppose to be helping me out with this but all in all I do not know what to do about this problem whether I should try again with another express replacement or just go with original plan which is to hold onto it until September and upgrade to the iPhone 16 Pro or Pro Max through either Apple or my phone contract.

What is the best option here do you think?

[Re-Titled by Moderator]