Meh, the feature is easily deactivable, the settings are clear and extensive. As far as ads go, it's one of the best implementations. Firefox still has no alternative in the privacy / user-centric space (don't mention Brave, I'm gonna get mad). Mozilla has done a lot for the web, I can give them some slack for exploring different revenue models. Still, I'm going to keep on eye for this kind of practices in the future…
Just imagine the meltdown if Google or Microsoft built that in. Somehow, Mozilla always get the slack and a couple of months down the road they are the saviour of the privacy world yet again.
Like with Firefox, you have to change your preferences if you want privacy.