Worse, they can pick whistleblowers, people who attempt to unionize, people who have harassment claims against the company, and ask it to retroactively come up

Worse, they can pick whistleblowers, people who attempt to unionize, people who have harassment claims against the company, and ask it to retroactively come up with a legal justification for firing them that would pass muster if challenged in court. It would be for sure a nightmare if it's automating the thing some companies do where they constantly hire their "worst performers" -- but they're doing it anyway with manual labor. The worse thing is that it makes it much more possible to justify firing someone for deceptive reasons in order to avoid anti-discrimination or harassment claims. This enables much more, because screenshots to comb through for dirt exist where they otherwise would not.