Ballot harvesting was rampant especially in inner cities. Many of those ballots had no signature.
What also happened was vote counters would fill in the dot for Biden when it was meant for Trump. Vote counters are not allowed to mark ballots, totally illegal. The machine would then cancel the ballot out and even though the vote was given to Biden, it took away a legit Trump vote. When the machine see’s both circles marked, it voids the ballot.