Meso drops drop the wrong 'icon' if you will. May not be a big deal to most but it's always been an annoyance to me. I believe this is caused by multiplying the meso drop after the packet's been sent.
I assume you mean that mesos dropped by monsters display as Bronze coin: 0 ~199 Gold coin: 200~ 399 Bundle of cash: 400 ~ 3999 Sack of cash: 4000+ This is not a visual bug, also, meso drops aren't multiplied after the package is sent. Anyhow, I like this because it would be strange to get gold coins or even bundles of cash in Henesys Hunting Ground I. I actually tried to have the same scale with player meso drops, didn't turn out nice as Meso Explosion was affected by this. Conclusion. Not a bug.