From the view if the back of the cartridge, right like this.
When the BCG closes (with bolt in the barrel extension), it's turning the BCG counterclockwise (rotation from the rear of the gun, in the "round's perspective"). That sharp edged ejector is causing that "smear" you see in the brass, to the left (or, counterclockwise) from the big round piece of displaced brass.
When the BCG opens, it's turning the bolt clockwise - and that ejector is digging in on it's own indentation right there, and displacing that "hump" or sharp piece of brass, in a "moon" or semi-circle, to the left side of that ejector indentation.
Now, the ejector indentation is from a hot round - or something bad in your gas timing. The BCG is already trying to moved rearward, but that piece of brass is still locked in the chamber.
That sharp-edged ejector is WHAT is happening, but it's not necessarily WHY it's happening. That make sense?
EDIT - if you radius the edges of that ejector, you're still gonna have some ejector smears on that particular load - but it's not gonna chew up the rim faces like that.