I'm currently reading Whittaker Chambers' book "Witness", in which he goes into considerable details about the Soviet/communist "apparati" (plural for apparatus?) that were secretly set up in the United States in the late 1920's, 1930's, 1940's, and beyond.
These comprised the secret "underground", as distinguished from openly-declared "above ground" communist members and operations of the time.
It looks to me that following Mr. Trump's win in 2016, the leftists/democrat-communists took a look at the various states in which Mr. Trump unexpectedly came from behind and defeated clinton (PA, MI, WI, AZ, etc.), and set about establishing an underground apparatus in each of them with the goal of throwing the election in 2020.
I'm sensing that many of the "ballots" (particularly mail-ins) that were used to "turn" the results were probably extant considerably before November 3rd, but they couldn't risk sending them early for fear of discovery -- hence the push to extend the deadlines for accepting late ballots, knowing that by then they were "running out the clock".
They succeeded -- or at least that's how I see it.
This apparatus has now been "built up into an underground machine" in these respective states that will again be available to throw future elections -- by then probably further refined in their techniques.
We'll see if this is the case on January 5th down in Georgia...