I can't see your photo's. but have an idea of what you taking about.

The cam relief indent edge can get a bit corner-whacked if there is a great deal of slop between the cam and the carrier slot.  Instead of the cam turning right away as when the carrier starts to move back, the cam will run straight for a few thousands with the carrier, and catch the corner.  Although you don't like to see it, the problem is semi normal on commercial rigs.

As for the sides of the key removing anodizing off the upper receiver key slot, that is normal and will be self-limiting as the key mates with the upper track.

Bottom line is the B/C is going to mate with the upper receiver (read have it's way) and this is a normal function for break in. Keeping the upper bearing areas of the rifle lubed with CLP will slow this wear (read get a longer service life out of the parts), but it's going to happen on every rig.

P.S. Welcome to the site!!!