Just for the sake of argument (in other words, so I don't get nasty comments from the far far right) let's say that there is absolutely no doubt that Uncle Joe won fair and square.
He can STILL be a FRAUDULANT PRESIDENT if his mental faculties have worsened to the point that he isn't even in control of himself, let alone trying to run the country and, by extension, the entire free world.
Evidence? Ya, I'm sure you'll ask for it and I'm sure that you'll dismiss what I present. It's impossible to prove a negative. A few things that make any critical thinking person say "Hmmm?" is that he hasn't done crap without his handlers ready to pull the plug. No solo press conference. No address to a joint session of congress. Zilch, zip, nada. This hasn't happened in 100 years.
https://www.washingtonpost.com/opinions/2021/03/04/when-will-biden-hold-press-conference/
https://nypost.com/2021/03/04/biden-live-feed-cuts-out-after-saying-hell-take-questions/