Oh man I've been saying this for ages! Neal Stephenson called this in "Fall, or Dodge in Hell," wherein the internet is destroyed and society permanently changed when someone releases a FOSS botnet that anyone can deploy that will pollute the world with misinformation about whatever given topic you feed it. In the book, the developer kicks it off by making the world disagree about whether a random town in Utah was just nuked.

My fear is that some entity, say a State or ultra rich individual, can leverage enough AI compute to flood the internet with misinformation about whatever it is they want, and the ability to refute the misinformation manually will be overwhelmed, as will efforts to refute leveraging refutation bots so long as the other actor has more compute.

Imagine if the PRC did to your country what it does to Taiwan: completely flood your social media with subtly tuned han supremacist content in an effort to culturally imperialise us. AI could increase the firehose enough to majorly disrupt a larger country.