I understand that, but what they do with user data is governed by their Privacy Policy, which again, is unchanged. The ads they buy are the same Sponsored ones that show up on blank tabs—the ones that have been there since before they made that change.

They made the change to the ToS, because a California law expanded the definition of "sale/sell" beyond what most people understand the word to mean. There's enough vaguery in the wording of the law that the way Firefox works, it could land Mozilla in hot water the way the ToS were worded. It's stupid, Mozilla did probably the worst job possible communicating why they were making the change, and the internet freaked out.

I'm not saying you shouldn't leave. That's up to you. I've been running LibreWolf since then, because a company that has $37M in investments and pays their CEO $8M should have the means to have a decent marketing team, one that could warn them it would be stupid to abruptly cut out a section on selling user data. However, it's simply not true that they've suddenly joined ranks with the likes of Google.

Again, do what you want, but I hope people do it because they've been informed about the facts, not because the internet brought out the pitchforks again.