An updated list of Firefox settings to change in about:config to rid your Firefox of any AI activity:

user_pref("browser.ml.enable", false);
user_pref("browser.ml.chat.enabled", false);
user_pref("browser.ml.chat.sidebar", false);
user_pref("browser.ml.chat.menu", false);
user_pref("browser.ml.chat.page", false);
user_pref("extensions.ml.enabled", false);
user_pref("browser.ml.linkPreview.enabled", false);
user_pref("browser.tabs.groups.smart.enabled", false);
user_pref("browser.tabs.groups.smart.userEnabled", false);
user_pref("pdfjs.enableAltTextModelDownload", false);
user_pref("pdfjs.enableGuessAltText", false);