This is so utterly bogus. I've worked as an election judge in Minnesota in four elections and three precincts. The ONLY way there can BE uncounted ballots to be "discovered" is if they are arranged in advance to be "discovered" in the event of a close election.
"Discovered" uncounted ballots should NEVER be counted for any reason. They are outside the process that makes them valid, and are so every step of the way.
As to asigning them to specific "disenfranchised" voters, again, that's impossible as properly handled ballots are absolutely anonymous, even absentee ballots.
Notice how often they’re found in car trunks, and how often they overwhelmingly favor Democrats? You’re right, the chain of custody has been violated, and the ballots should be disqualified.