This is much easier said than done. What if her severance was significant? What if she needed it to survive? Meta's line is she was fired for "poor performance and toxic behavior" and a non-disparagement clause often cuts both ways; now instead of saying "she worked her from <start date> to <end date> this was her job title" they can publicly disclose she was let go for serious job failures. It doesn't matter if this is true, good luck getting a new job.