Some ballots have watermarks. So what? Lots of standard paper that anyone can buy has watermarks. There is no evidence anywhere that DHS has anything to do with any watermarks on paper used to print ballots. The DHS website is just stating basic information about what some states do to try to make ballot counterfeiting a bit more difficult.

Of course, many of these states are under Democratic control and even many states with Republican-controlled legislatures have government agencies staffed with lots of Democrats who don't hesitate to do illegal things to advance their political power. These staffers can order all the watermarked paper they want, and give it to anybody they want to give it to. And the staffers in charge of printing have all the information about anti-counterfeiting measures in the printing process, and can give that information to anybody they want to give it to.