I believe the article describes this the other way around. When the government prints money, it is deposited into the TGA. In this case, money earmarked for stimulus use. Due to the bickering between government entities the second half of 2020, much of the approved stimulus money was not distributed, and remains as cash on the TGA. Because this cash balance is more than law allows, if it is not disbursed, it needs to be removed from the TGA in the form of T-bills.
My posts are my opinion. Always trade at your own risk.