Ukrainian media reported this with reference to a source.
“Now the idea of economic reservation has been abandoned altogether, because the General Staff was categorically against it. But the $5 billion that will not go into the budget because of this needs to be covered with something. I think an increase in taxes will partially solve this problem,” the source said in OP.
According to him, the General Staff considered that “economic reservation” would not solve the problem with the shortage of personnel, would be perceived as an official payoff from mobilization and would only cause a negative reaction in the army.