What happened
1. Wednesday to Saturday A lot of material was circulating that indicated election fraud, accounting for about 10% of all citizen content. and 1-2% of all US VPVs. The process of incitement to violence also started.
2. There were dozens of staff monitoring this, and FB launched ~15 measures before the election, and ~15 others in the days after. Most of the measures made existing procedures more aggressive: for example by lowering thresholds, making penalties more severe, or expanding the qualifications for existing measures. Some of the measures were qualitative: reclassifying certain types of content as infringing, which previously was not.
3. I think these measures will reduce at least 2X the prevalence of infringing content. They did however suffer collateral damage (the removal and removal of non-infringing content), and the episode caused noticeable outrage by Republican Facebook users who feel they are being unfairly targeted.