Yesterday was another article on ballot harvesting being the culprit, but I think it’s a contributing trick along with other sneaky Democrat stunts such as same day registration/voting.
It's a multi-front assault - that way if they get called on any one piece they can claim it is "no big deal" and "Republicans are engaging in voter suppression."
And they have a point, in a way. Today's electorate is so dumbed down that if 100% of them turned out, the Santa Claus Democrats would probably win every race 75-25. Republicans need the uninformed to stay home to have any real chance.