"Waterfox is thriving" eh? Sounds like wishful thinking to me.

I get the loss of the XUL extensions is annoying for some people, but the rest of it sounds like pointless UI faffing of exactly the same kind people criticise Firefox for.

> The project is not without its own controversies, such as its purchase by ad vendor System1.

Pick your poison:

- directly owned by ad company

- owned my incompetent mozilla (financially backed by biggest ad company).

I'm not gonna lie I'm choosing Mozilla on this one.

Related discussion about LibreWolf: https://news.ycombinator.com/item?id=29106155.

> An interesting side-question is how the open-source Firefox OS turned into the proprietary KaiOS.

The MPL allows for non-open-source use, right? As long as patches to the original source are made available.