LibreWolf seems pretty fast about it. The difference is only ever a matter of a few days for routine updates.

For example, it looks like Firefox 141 with the AI stuff was released on July 22, a few weeks ago.

My LibreWolf install is 141.0.2 My Firefox install is 141.0.3

That difference is worth it to me to know that various things I don’t want have been removed from the code entirely, and that I can keep a completely default install of Firefox and/or nuke and replace that install whenever necessary.