In Diocletian’s time, in the year 301, he fixed the price at 50,000 denarii for one pound of gold. Ten years later it had risen to 120,000. In 324, 23 years after it was 50,000, it was now 300,000. In 337, the year of Constantine’s death, a pound of gold brought 20,000,000 denarii.
It doesn’t matter what a currency is backed by, the controllers of the currency can always debase it by changing the exchange rate.
The only way to protect yourself from currency debasement is to own gold or silver.