Just chiming in here, I returned my 13 Pro Max thinking this was an issue. The replacement phone had the exact same gap, I had this on my 12 Pro Max but did not notice the metal. I read up on it more, every phone will have that "gap" somewhere as a super tight seal between the glass and chassis would result in cracks. Essentially, it is normal.
To those that are saying you paid X amount for a phone that has this gap, unfortunately you are going to be hard pressed to find any premium phone that does not have this issue. I (briefly) tried to switch to the Galaxy Fold 3 in between the iPhone 12 and 13, the Fold 3 had significant light bleed on the front display and a quick google showed that many Samsung users had this issue across their entire line of devices.
I prefer an Apple gap to the Samsung gap where light is actually seeping through the gap, at least with the iPhone I do not notice it unless I look closely. Going to the Apple Store tomorrow to replace one final time (Sierra Blue is rarely in stock lol), and if it the gap is present I will just live with it.