Like facebook, twitter, and reddit, where there is a concerted effort, that has people working on how to specifically target the people on each one, and understand the differences in their use, and users? No, of course not. Are there bots spreading national, and corporate, propaganda on lemmy? Yes. They are literally everywhere you can make posts. I am willing to bet there are tiny fora out there, with like 10 users, that occasionally sees bot spam.
You can totally make programs to scrape the internet for places that have posting functionality, crawl the scraped sites, and auto post. These already exist, and you can buy them, or get them shared to you from various sources. Most of these sites use template software to run their sites. It is not nearly as difficult as people might think to accomplish this. Bot traffic is 50% of internet traffic.
Is there a group somewhere, sitting in a government facility, working on how to best infiltrate Lemmy? I really doubt it. Do these places have general function bots that make it on to lemmy, and even smaller places? Yes. In fact, bots are causing a growing number of small sites to experience what is, essentially, DOS attacks, because of how much traffic suddenly hits the site once the scrapers/auto account makers/etc. have found it.