When money becomes detached from value. If the government can just print more money the money becomes worthless. If the government limits the money growth to the increase in GDP the money retains its worth.
Milton Friedman famously said, “Inflation is always and everywhere a monetary phenomenon in the sense that it is and can be produced only by a more rapid increase in the quantity of money than in output.”
In my long life, Milton never asserted anything that was not accurate, nor blindingly obvious to anyone with an IQ above wet earth,