Personally I don't think the narrative of Trump supplying watermarked ballots to the states is at all believable. Why in the world would the swing states who admittedly had a massive plan in place to cheat not see through that and simply not accept them? On very reasonable Constitutional grounds as well I would think.

Just sayin' ... I need convincing on that one

From memory, without digging at all…. I’m thinking this had to do with standards on paper, paper type, that was contracted only to official printers for federal ballots. The printer from Arizona, mentioned even in prior elections is Runbeck. prints for other states as well. They’re used UV or black lights during one of the audits, supposedly looking for watermarked paper ballots. Here’s one link popped up while looking for printers name. Remember the printer in Syracuse or Rochester..up north New York burned down. Suspicious activities with Printing companies! new rabbit hole for some.
https://www.abc15.com/news/region-central-southern-az/maricopa/behind-your-ballot-how-election-ballots-are-printed-and-verified-in-az