Biden's order, and b) in many cases still have parole, which isn't the case in the Fed system. And even that article confirms that ultimately parole boards, not the prisons, determine how long someone stays (although prisons more likely to report infractions can impact those rulings), and that the prisons "know they can’t just keep inmates longer".

If private prisons are not living up to their obligations in terms of conditions, and that's not being enforced by the states, getting rid of them and turning that back over to the states (or the Feds in this case) isn't necessarily a better solution. Again, there's a reason things get outsourced, and it's not to have worse output and higher costs.