I can't get into the US-local conspiracy-mongering, but I'm not sure how you've missed social media becoming a hot-spot for election-day information/misinformation?
Shutting down social media has gone to the top of the list for regimes either "attempting to fabricate positive election results" or "attempting to combat the spread of misinformation about elections".
More sympathetically, for better or for worse (definitely the latter) there will be people trying to look up election information ("what are my local polling hours", "who is on my ballot") on social media websites, who will now not be able to be guided to the correct information.
Shutting down social media has gone to the top of the list for regimes either "attempting to fabricate positive election results" or "attempting to combat the spread of misinformation about elections".
More sympathetically, for better or for worse (definitely the latter) there will be people trying to look up election information ("what are my local polling hours", "who is on my ballot") on social media websites, who will now not be able to be guided to the correct information.