I do not think unreadable ballots is an issue that favors one party over another.
It is the
recount that matter.
In Spanberger's own election to Congress in 2020, she was behind on election night, behind on the day after (and the margin of victory at that point was known to be about 7,000 votes), and then a thumb drive with 15,000 votes was "discovered" in heavily-Democratic Henrico County. Spanberger eventually won by 8,270 votes.
In the
Washington State Governor's race in 2004, Dino Rossi was
certified as the winner. Uncounted ballots were discovered in heavily-Democratic King County (Seattle), and Christine Gregoire eventually won by 129 votes, once humans examined all the ballots and applied some human judgment to the questions of "Should this rejected ballot have been considered in accordance with state law?" and sometimes, "What was the voter's intent?" (In Virginia, voters "bubble in" a small circle next to the candidate's name, but if the bubble is not completely filled in, the computer might not count that vote for that candidate, but, as long as there are no more more marks in the bubbles for any competing candidates, a human can discern the voter's intent.)
This is why, in close races, human recounts are important. If Spanberger signs this bill, this will become illegal in Virginia.