Of course there was security measures on the ballots. Assuming that they exist isn’t confirmation bias, it’s common sense. The ballots are legal documents akin to money or naval logs. Establishing basic counterfeit protection and secret security verification markers is as basic a basic gets.

And just like legal tender, why would the issuer ever fully reveal the security measures? This would defeat the entire purpose of the protection.

I don’t know if we will ever find out all the details, what if they want to use them in the future?