The right question: Why was there no inflation in the United States or Europe in the 2010s?
The anomaly is not the return of inflation, but the presence of a ten-year period without inflation during which central banks were able to pursue objectives other than price stabilisation. Why was there no inflation in the 2010s when there was inflation before this period, and also now? The answer to this question is actually quite simple. There was no inflation in the 2010s because: Commodity producers had not organised themselves to drive up prices; Wage earners' bargaining power had become very weak prior to the COVID crisis. If these two characteristics of the economies are reversed, and as productivity gains are low, the risk of inflation becomes very high.