What are the ways of measuring inflation and why is its measurement impacted so badly by the covid and I think some places are using it as the projection for the inflation? Or is it something to do by the weighting bias? Any suggestions will be great! Thanks .

Eg

The COVID-19 pandemic and the measures enacted to contain it have led to a standstill of public life and a severe downturn of economic activity in many countries, including Switzerland. The measures implemented by the Swiss Federal Councilincluding lock-downs, mobility restrictions, and social-distancing ruleshave greatly affected consumer expenditure patterns. Non-essential retail outlets and many service industries such as restaurants and bars as well as entertainment and leisure facilities were temporarily closed. Public transport services were reduced. Only grocery stores, pharmacies, banks, and post offices were allowed to remain open (Eichenauer and Sturm 2020). During the roughly 2-month1 lock-down period, the consumer spending was thus severely restricted.

Sudden and profound changes like these can introduce significant bias in the consumer price index (CPI) used to measure inflation. The CPI is compiled on the basis of expenditure weights that are kept constant within a given year, reflecting the purpose of the index to measure changes in prices only without accounting for adjustments in consumption patterns. Most national statistical offices update their CPI expenditure weights once a year, often with lagged expenditure data

This may give you some hints

https://sjes.springeropen.com/articles/10.1186/s41937-020-00057-7