Firefox fork 'Pale Moon' releases v28, first major version since 2016
palemoon.org
palemoon.org
https://www.howtogeek.com/335712/update-why-you-shouldnt-use...
tl;dr Maintaining the security of a browser is a massive job that even a 1000+ developers struggle with. Pale Moon is maintained by one person and does not benefit from hundreds of Firefox's security fixes (because it's a fork).
While Palemoon was forked from firefox, the current codebase isn't stagnant, it is updated quite frequently.
If someone misses some old dev app, like Selenium IDE, then I can understand that choice. But that'll be a tiny niche.