The 2020-2022 inflation spike wasn't due to following MMT based spending policies though. Slamming the brakes at 100mph may certainly have bad consequences, but driving at 100mph in low visibility conditions was the problem, not braking before you hit something.
The fact is everyone knew the combination of supply chain disruptions, remote work, and the changes in spending habits would eventually produce inflation, and yet we kept pumping money in. Every economic school would have advised against that course of action. MMT only calls for spending to keep pace with economic growth, not to run the money printers as fast as you can.
Economic theories, like scientific theories, are successful if they correctly predict what will happen if you do X. If the theory of gravity predicts that you will fall to your death if you jump off a cliff, it's not a failure of the theory of gravity that it doesn't tell you how to levitate after you've already jumped.