Please refer to this article:

https://www.ceps.eu/measuring-price-stability-in-covid-times/

The article discusses the use of alternative measures of inflation for macroeconomic policy response to the Covid pandemic in the European Monetary Union (EMU). The article compares three measures of inflation: GDP deflator, the harmonized index of consumer prices (HICP), and the core, which is calculated the same way as HICP, but excludes energy and food items.

The article argues that policymakers should pay attention to GDP deflator as well as HICP. According to the article, why did attention to GDP deflator matter during and after the financial crisis of late 2000s?