That's exactly what's changing; Mozilla is moving from a strictly curated model to a more open model. I wouldn't say support is completely arbitrary because ex

That's exactly what's changing; Mozilla is moving from a strictly curated model to a more open model. I wouldn't say support is completely arbitrary because extension features and requirements between mobile and PC are different; there's a reason Mozilla is trying to get devs to test their extensions on mobile before they launch. But there are certainly a lot extensions that should work fine, especially as more extensions start to move to Firefox's version of Manifest V3, and the existing curated model locks them out. It is (was) a major failing of the browser on mobile devices. My understanding is that the December update will move Mozilla from curating a small number of allowed extensions, towards a model where developers just specify which platforms they want to support. And my understanding is that the only reason that number is going to be 200 instead of thousands is because only 200 developers so far have checked to make sure their extensions work with requirements like non-persistent background pages and with mobile layouts.