After 3 Years the Fed is Undoing its Repo Market Bailout

Three years ago, the federal reserve started to bailout the financial system yet again (not with QE), when the repo market blew up and they started buying treasury bills to bailout the repo market. Now at the time they said this wasn’t QE because they said they were only buying bills, not regular treasuries. So far, they haven’t unwound back any of that bailout until this month. This month will be the first time that the federal reserve will sell back those bills to the market. So far in their tightening they haven’t let any of those bills go and now they’re going to start doing it. But why? Is it because they think the economy is strong enough to manage it, or because they’re trying even harder to withdraw liquidity out of the system?