List of the bugs:
1. Devs accidentally put banner rate up as 7% instead of 0.7%
2. Mashiro and Aru Banner giving Shiroko shards as well.
3. Coupon abuse (repeatedly using the coupons).
4. PvP/Tactical Challenge and Raid/Total Assault hacking.
Never change, NAT GAMES. It's just like in JP server.