It's just vault from what I've seen Someone pointed it out in world chat months ago and I've been watching it since. I did had a bunch of stupid theories as to why it was happening, all debunked now though
Well the actual reason this is happening is pretty stupid too. The database is storing these large values in a way that they are no longer treated as a numerical value and that is messing up the sort. We know how to fix this but this requires a database upgrade which should happen in the near future. Until then the sort on Vault and any other field with really large values may not be accurate on the World Leaderboard. These issues do not affect your Friend Leaderboard however. Why? Just cause... More accurately because we do the sort ourselves and don't rely on the database. This method is sadly not feasible for the volume of World LB records.
lol forgot about this... that was actually one of my stupid theories. You guys never anticipated people reaching the quintillion mark and that's why it just says 1,000 quadrillion instead. haha *shrug*