This is already something they insisted on leaving enabled by default because they knew no one would opt into it. They knew full well that this isn't something people want. Mozilla is an ad-tech company now. Instead of improving firefox they spent a ton of money buying an ad company created by facebook employees. They're going to claw back a return on that investment and they're taking it from Firefox users.
They simply do not care about the privacy of Firefox users. There is zero chance that this is as far as Firefox goes in violating your privacy. Expect more anti-features, expect things you disable in about:config to re-enable themselves after updates, expect more tracking that you can't disable, expect more invasive forms of tracking, and expect your ability to block ads on firefox to get increasingly limited until it becomes impossible. It's all downhill from here.
