On iOS, only Safari can use content-blocking apps installed from the App Store to block content on the web, but third-party browsers are allowed to build in their own ad-blocking solutions. We know this, because Firefox Focus does exactly that, and Edge for iOS even goes as far as to bundle in Adblock Plus. Firefox for iOS needs to use Firefox Focus as a built-in ad-blocker, and Firefox Focus needs to be phased out. There's no reason to have two Firefox browsers for iOS when one of those browsers could literally just be a feature of the other one.