>>715377234
In order to save resources the developers of Destiny 2 came up with the solution to have all gun animations be the same regardless of the type of gun. By making only one animation they were able to decrease file sizes for the hundreds of guns found in the game.
They would simply turn on or off the specific components needed for the weapon. However in the early days of Destiny 2 almost all guns ejected bullet cases even ones that weren't supposed to, like energy weapons and revolvers. This was because they simply forgot to turn off that specific component in the weapon animation and it took nearly 4 years for them to fix it.
It also led to misconceptions in the lore as certain guns were not supposed to use regular brass bullet casings, but in game they clearly were.