A few settings you may wish to consider for your firefox’s about:config page.
browser.ml.chat.enabled = false
browser.ml.chat.shortcuts = false
browser.ml.chat.shortcuts.custom = false
browser.ml.chat.sidebar = false
browser.ml.enable = false
browser.tabs.groups.smart.enabled = false
I wish Firefox would make AI crap be addons as opposed to built into the browser.