> Due credit to Mozilla here: this chatbot integration is easy to turn off. You can do it via the GUI – it's on the Settings screen behind the last button, Customize Sidebar.

The instructions here do not pan out whatsoever, at least in Firefox v141.0.3 EME-free 64-bit on Windows, MacOS, and Linux.

What you need to do is open the sidebar, go to the bottom, and click on the gear icon there at the far left. Then the “customize sidebar” settings will open on the right of the sidebar’s own content, and provide you with the required options.

Nothing exists within the normal settings pages that can bring this up. Only by going through the sidebar can you get to this.