I would measure the diameter of 10 bullets. Maybe something is off there.
I've picked up a lot of Glock 40 S&W brass. It never had the square mark as far as I know. It did have drag marks and your drag marks are about right for a max or near max load. Maybe the square marks are the next level of hot. Also, Glock's are famous for oversized chambers. Maybe it is time for a chamber cast.
Last, the crack seems to have stopped where the brass was "Glocked". . .weird.