Fiat money has been inflated by a 400% since 2008, that is the inflation, but why the price of everything did not rise at least 200%? This just proved that inflationary money will not necessary cause price rise, when majority of people are in panic mode, the money supply can increase by 10 fold without causing any significant price appreciation on goods and services, since everyone is saving
The price level is typically decided by consensus
The other reason for this is fractional reserve banking, during the recession, bank reserves increased and the amount of active loans dropped which lowered the effective money supply even though there is actually more currency in circulation.
It's an illusion, and unfortunately it's temporary.