Tried to pick an equipment (clothes armor) while in full backpack, for some reason the items just "flies away"? Haven't tried to replicate it in other scenario.
if you try to pick up an item, can't, and there's a second item underneath it, this will happen. in vanilla it's a bug, in shattered it's considered intended behavior (it was left in on purpose, even when the code for item heaps was rewritten)