That's strange, which OS? I am on Arch and also on 145 and I get the "Ask an AI Chatbot" in the context menu. The settings used to work in the past so I am not sure what's going on.
I believe these are all the settings I have disabled for AI:
browser.ml.chat.enabled
browser.ml.chat.menu
browser.ml.chat.page
browser.ml.chat.page.footerBadge
browser.ml.chat.page.menuBadge
browser.ml.chat.shortcuts
browser.ml.chat.sidebar
browser.ml.enable
browser.ml.linkPreview.enabled
browser.ml.pageAssist.enabled
browser.tabs.groups.smart.enabled
browser.tabs.groups.smart.userEnable
browser.tabs.groups.smart.userEnabled
extensions.ml.enabled
sidebar.notification.badge.aichat
Am I missing anything?