This was a problem everyone was beginning to notice, especially those who used Worldly Energy directly like Roma, Hikari, and Rina. Those who relied on mana weren't affected as much as they automatically converted Worldly Energy to mana, at most wondering why their MP regen got forcibly slowed despite all the buffs they had on them.
Eva's lips pursed. This was one of the mechanics most players of Boundless dreaded and felt that the game could happily do without... its crazy fascination with realism!
In this case, the pseudo-finite nature of useable energy!
Yes, Worldly Energy was eternal and would restore itself after time. However, the current rate at which the various beings in the Field Zone were absorbing and converting it into other forms of energy exceeded its recovery rate, making it temporarily finite.
Those who pondered over the rules of Boundless would all eventually contemplate where exactly that so-called Worldly Energy would come from.