So they've said. It should be opt-in not opt-out.
How much will they scrape before you turn it off? What will it scoop up immediately on a fresh install? And what will it grab from your system on an existing upgraded install?
Willing to bet the answer to both of those is not "nothing".
Although after the ToS update bullshit earlier this year no idea why anyone even halfway paying attention didn't switch to an alternative that's more privacy focused already.
Oh I did. I don't believe a goddamned thing they say at face value, especially with the changes to the ToS back in February. The new Mozilla CEO was the General Manager for Firefox previously, so there is no new perspective here.
Until the AI slop update is released and their claims can be independently verified, there's no reason to believe them