Deconcentration is suddenly 100x the previous rate after level 50
This is actually NOT a bug. This is a soft cap preventing price reduction on orbs from getting carried away. Having anything above a 50% discount would severely hinder the event balance.
Power Orb costs are different for certain players
There were slightly cheaper costs at lv 19, but they sky-rocketed into the bajillions. This was rectified by costs of 1000 M (1 billion) for orbs 20-25.
However this allowed players to earn their level 19 power orb for a significant discount.
The balance takes effect only on newer instances.
There will not be retroactive balancing on this, sorry.