I had UBO disappear once or twice from my desktop Firefox, but that appeared to be a bug of some kind. Never vanished from my mobile version, and AFAIK it's nev

I had UBO disappear once or twice from my desktop Firefox, but that appeared to be a bug of some kind. Never vanished from my mobile version, and AFAIK it's never been removed from Mozilla's add-ons store. Mozilla also doesn't stand to gain anything by forcing you to view ads. Google does. That's why Firefox Mobile has historically been the mobile browser that lets you install add-ons and ablockers, while Chrome for Android has not.