If one of these is a backpack, then I think it'll be the health pack. There's an unreleased pack in the game that hackers have datamined that appears to be like the supply back, but just full of stims instead of ammo. While it could be hacked-into a live game, it wasn't completely functional yet.

Dataminers have also recently noted that this health pack has somewhat recently been modified, too. There used to be a passive buff for this item that would gradually heal you, and that seems to have been removed in a recent patch. So only because this unreleased item has recently seen some behind-the-scenes action, that I suspect that we're getting it soon.