The best explanation I heard after the great financial crisis (i.e., not recently) was that during that crisis, the Japanese bubble economy of the 80's, and to a lesser extent the dot com crash, huge amounts of credit (marked to market) were destroyed. If you look at the total supply of money and credit marked to market, there was not much, if any, increase.
Yep. Since the 80's up to the 10's Japan has printed almost enough to cover for the reduction on private credits, just a bit less, so they got deflation.
I believe this is a well accepted thing, with basically everybody that accepts that private credits are impactful enough to be important accepting it (what is not universal, but nobody else has an explanation).
The lack of inflation on the US between 08 and 20 is much harder to explain.
That was not true of the pandemic.