The AI chatbox is about the browser.ml.chat.enabled pref. You can control all "browser." pref via policies.json. See the Preferences policy.

• https://mozilla.github.io/policy-templates/
• https://mozilla.github.io/policy-templates/#preferences

That doesn't seem to be working. I added "browser.ml.chat.enabled": false into my existing policies.json and restarted Firefox. The AI chatbot I had left open was still there, and going to the Firefox Labs section of settings still showed everything enabled as I had manually set it to test this out.

Is there another setting required to prevent it?

Did you look under the policies.json header of the Preferences to see what you need to add? It doesn't work like what you wrote: "browser.ml.chat.enabled": false There are likely errors reported in about:policies.

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-policiesjson
• https://mozilla.github.io/policy-templates/

{
 "policies": {
    "Preferences": {
      "browser.ml.chat.enabled": {
        "Value": false,
        "Status": "user"
      }
    }
  }
}