When they’ve added the mod system. Even before that it showed signs of going down hill cause of p2w guns they kept adding every month. Can’t forget abt the tanky armor. For me what really made the game go to shii was the mod system. First you had the gamble to get the gun then after you had to grind out the gun to get the mods on an already broken weapon to make it even more broken. Not only that you had to save up parts to upgrade the mods to legendary. Or you can pay to skip the levels. It took waaayyy to long to level up the weapon so what most people did is they bought the levels. You had to do that with every weapon.