My first reaction was that a 9mm Parabellum round wouldn't fit in a 9mm BL chamber, but a check of the cartridge specs shows it just might, likely wedging in because the 9mm BL case is actually longer than the 9mm P. I am surprised that gun held up to the punishment. I would be very careful about shooting it, and not just because of the barrel bulge.
The use of the wrong ammo didn't cause the bulge, though; that comes only from firing a bullet into an obstructed barrel.
Too bad. The gun might be shot safely with the right ammo, but if the bulge is pounded out, the further bending of the steel could weaken it enough that IMHO the gun should not then be fired.
(That pistol is an early striker fired DAO pistol; if it is odd, so is the Glock.)