Flattening of the Phillips Curve

Why does low unemployment no longer lift inflation?

https://www.economist.com/schools-brief/2020/08/22/why-does-low-unemployment-no-longer-lift-inflation

Inflation is losing its meaning as an economic indicator

https://www.economist.com/special-report/2019/10/10/inflation-is-losing-its-meaning-as-an-economic-indicator 

Update: The Great Inflation Debate Is Heating Up with Trillions at Stake
https://www.bloomberg.com/news/articles/2020-08-25/the-great-inflation-debate-is-heating-up-with-trillions-at-stake