@firefoxwebdevs "Without the user's request" is quite ambiguous, though. I'm reminded here of Google, which put the AI tab before the Web/All tab, displacing it so that people would unintentionally hit the AI button and "request" it. It's a small and plausibly-deniable change that nevertheless violates the user's boundaries, and difficult to call out and stop even internally within a company or team. I've seen many companies and software do the same thing.
A genuine opt-in would, in my opinion, look something like a single "hey do you want such-and-such features? these are the implications" question, presented in a non-misleading way, and if that is not answered affirmatively then the various UI elements for "AI" features should not even appear in the UI unless the user goes and changes this setting. It's much harder for that to get modified in questionable ways down the line, and reduces the 'opportunities for misclick' to a single one instead of "every time someone wants to click a button". It also means users aren't constantly pestered with whatever that week's new "AI" thing is if they've shown no interest.
Such a dialog could still specify something like "if you choose Yes, Firefox will still only download models once you try to use a feature", to make it clear to users that it's not an all-or-nothing, and they can still pick-and-choose after selecting 'Yes'.