There were no "blank ballots". There were ballots where voters chose NOT to vote for President but voted for down ballot candidatesBecause I do not know. I know they are illegal and need to be eliminated. If the numbers they have are greater than the margin of victory (which they are) the election needs to be decertified.
AND THERE'S NOTHING ILLEGAL ABOUT THAT
In competitive Arizona, North Carolina, Nevada and Michigan, tens of thousands opted for neither Trump nor Biden but "undervotes" were down from 2016.