We've also had four big rounds of Quantitative Easing from the Fed since the financial crisis, with the most recent coming right after the pandemic.
Central banks could reduce their balance sheets significantly more (and until recently the pace was pretty quick), but given where things are today it will undoubtedly be pretty politically unpalatable to do so (bond markets puking, making deficits even worse in the face of an inability to cut spending).
Easier said than done, I think.