It's all just right wing propaganda, convince the population 'Biden is bad, take your ball and go home' and you suppress the vote. They can't institute poll taxes or tests any more, and with vote by mail becoming commonplace they can't rely on showing up at polling places with guns to suppress turnout.
When more people vote the left wins, and that's what the right are afraid of, thus the persistent drumbeat of 'stay home if he's not good enough'.