It is the exorbitant privilege. It is a bit hard to find good discussions of the mechanism because it gets political very quickly. But in essence if the US prints the whole world absorbs it, if Japan prints it stays in Japan.
Price = demand/supply.
Why? It would be quite odd. Certainly Japan has generated far more currency and debt over the last 35 years while inflation stayed low (and the relative value of Yen stayed high). I don't see any explanation for that here any more than the yearly gyrations of other currencies crypto or fiat.
But as I wrote. This is a controversial subject. And there are economists out there who will tell you that the special status of the US dollar makes no difference at all and this de Gaulle guy just was upset about losing some colonies.