Why didn't the rapid increase in the monetary base between 2007 and 2017 result in an equivalent increase in the money supply?

Explain why the Fed had to rely on non-conventional monetary policy in the wake of the financial crisis of 2008?

Explain why the Fed is again forced to rely on non-conventional monetary policy in the wake of the current financial crisis associated with the COVID-19 pandemic.

resource : https://www.brookings.edu/research/fed-response-to-covid19/