That has nothing to do with the gun performance, but the changes to ground targets. The gun has been unchanged since they added drag, but didn’t add realshatter
But for example .50 cal and american 20mm guns doesn’t have that problem with pillboxes and tanks. Only german 20mm guns.
GSh23L has always been the strongest in that regard, and it is, still, to this day, the best damage dealing gun below 30mm, still surpassing NR30’s with great advantage. NR30’s will probably tear a wing with three shells, GSh23L will cut your plane in half and kill the pilot with only a single shell hitting your aircraft.