It may be a side effect of scaling. That's just an assumption. The algorithm used to determine what will be displayed and to ensure that names will not overlap

It may be a side effect of scaling. That's just an assumption. The algorithm used to determine what will be displayed and to ensure that names will not overlap may also not be deterministic, or not completely. Meta-balls kind of computations can typically generate a different output based on where you start to aggregate stuff. Given the need to handle this at a very large scale, one could imagine that different machines are doing their map/reduce thingy on their own, and that the first responding would be taken into account first, etc.