That's not what MMT says. It says that excessive spending in the economy can create inflation. A possible way to compensate (not the only one) is to raise taxes.

But it doesn't say that the only cause of inflation is excessive spending. That idea is a monetarist fantasy, who are able to keep saying that even in the middle of a pandemic, with a logistic collapse, an energy crisis and a major war. Still, they think that everything will be OK raising interest rates and taxes.

Totally crazy. I'm curious to see what they will say if we see something a lot worse, deflation, in the next years.