I’m not sure what the terms of the deal were. but I am sure if the payment for the 7% interest was to be made in the same coin and loans were to also be made at the same rate if not higher, then all of those coins would appreciate in value. what causes inflation and therefore depreciation is printing too much money. What causes appreciation for a coin is scarcity that can be created by interest rates, especially super high ones. When not enough coins are being minted And interest is accumulating Then it creates a deficiency in supply.