During the pandemic (and also during the response to 2008 recession) the Fed has been injecting cash into the market by buying Treasury securities and mortgage-

During the pandemic (and also during the response to 2008 recession) the Fed has been injecting cash into the market by buying Treasury securities and mortgage-backed securities. This is what "Quantitative Easing" is, and is a relatively new tool used by the Fed that they started leaning on when interest rates really could not go much lower. (https://en.wikipedia.org/wiki/Quantitative_easing https://en.wikipedia.org/wiki/Quantitative_easing) Now the Fed has a really large backlog of these securities, and they are starting to unwind that by selling those securities off, effectively removing cash from the economy and slowing down economic activity (and therefore hopefully inflation).