Because Destiny 2 is a looter shooter, the way loot can be managed by players is important, which is why the community has been very vocal over the years about increasing vault space. Doing that would allow players to store more items and carefully select which armor pieces they want to keep and which to dismantle, as well as which weapon rolls can be good enough to keep for later. Still, one of the biggest boons of Destiny 2 is that it allows third-party apps to handle players' inventories and vaults in a way that makes it all quite simple and straightforward.
Prior to this addition, transferring gear over to alternate characters required players to travel to the Tower, place the items into the vault, log into the other character, travel to the vault once more, and pick up everything. This was incredibly time-consuming, so apps like Destiny Item Manager became extremely popular in the Destiny 2 community. For a long time, it was believed that apps like DIM simply couldn't make items disappear because of how the game's API works, but recent evidence proved otherwise.
Destiny 2 YouTuber and content creator Cheese Forever shared a video that explains what happened to a Guardian whose Masterwork chest piece simply vanished. Other players didn't believe that it could have possibly been Destiny Item Manager because there was no track record of something similar ever occurring, which led them to believe that the player had deleted the item by accident. However, DIM developers recently admitted that it was a bug caused by the newly introduced ability to change ornaments for Destiny 2 armor from DIM itself, rather than in the game.
In fact, a previous iteration of Destiny Item Manager allowed players to apply specific ornaments to armor pieces even when the base skin for that item was the same. This was seen as an error from the API, considering that players cannot do the same thing while logged into Destiny 2, and the game ended up deleting the item. This issue seems to be solved for the time being, but Bungie, unfortunately, doesn't have a way to reimburse players for items lost this way.
Considering how many Destiny 2 players have been lowering their Power Levels to help newcomers in Dares of Eternity, recently, and seeing how many of them will have used DIM, it's not impossible that more items were lost this way. Caution is advised when using DIM and other third-party apps, especially their features that allow players to change Shaders or ornaments, but the cases reported by the platform should be isolated.
Destiny 2 is available now on PC, PS4, PS5, Stadia, Xbox One, and Xbox Series X/S.