PDJT told us back in June.
Donald J. Trump
@realDonaldTrump
RIGGED 2020 ELECTION: MILLIONS OF MAIL-IN BALLOTS WILL BE PRINTED BY FOREIGN COUNTRIES, AND OTHERS. IT WILL BE THE SCANDAL OF OUR TIMES!
7:16 AM · Jun 22, 2020·Twitter for iPhone
https://twitter.com/drawandstrike/status/1324123192529723392
Remember, DHS printed the ballots.
They have radioactive isotopes and watermarks and other identifiers. This isn't advertised broadly, but the info was out there.
Ballots printed by other parties or foreign countries won't pass muster when challenged in court.