It's a bug, when a player dies there are a couple elements that don't disappear such as glasses/custom eye, watches, plushies, ...
For some reason some of these elements (like glasses) can be glowing orange, and they will often move slowly in 1 direction in 3D space (can be any direction, including up/down) and will phase through walls.
Could be something else of course but it 99% sounds like that












