here's a few settings you may wish to consider for your firefox's about:config page.

[Gast]

here's 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
extensions.ml.enabled = false

if your firefox is recent enough, you might want these to disable AI tab groups too (thanks @ilmari!)

browser.tabs.groups.smart.enabled = false
browser.tabs.groups.smart.optin = false
browser.tabs.groups.smart.userEnabled = false