She hasn't been sentenced yet. We don't know what the terms of her deal are but they almost certainly involve leniency in the sentencing. Her lawyer likely tried to make a case that the big bad evil SBF sexually manipulated her into committing fraud and actually she's the real victim here.
Leniency is a relative term. It's relative to the size of the harm, number of victims, her centrality to it, etc. If there's a for sure bet to be made here, it's that she will be spending many years in prison for this. Just not her whole life. That's what leniency here means.
Also the thing to consider as well is that any management level trust position in a white collar setting is off limits to her for many years after that as well. On account of people being slow to entrust ex-cons with responsibility.
She'll make way, way, way more money selling her tv/movie rights to Apple or whoever makes the definitive documentary-drama on the matter. Like 'F you, never work again' money.
Mostly articles like https://lawprofessors.typepad.com/whitecollarcrime_blog/2015... (this case is also being prosecuted by SDNY) and a general expectation that she won't go scot free (so not just 21 days) but also that SBF is the one they really want to put away.
