From Waterfox to LibreWolf and Pale Moon, there's a browser for almost every Mozilla dissenter.
Firefox 156 is trickling out to users. The release notes only mention two new features: for Mac users, there's now an option in Settings to automatically launch the app at login.
Users who have chosen French, German or Italian will now find suggestions from Wikipedia in their own languages – along with potentially less welcome ads from Mozilla partners. If you don't want such suggestions, you can turn them off in Firefox Suggest settings.
Thunderbird 156 offers more troubleshooting info in the event of problems with OpenPGP, and more options for OAuth authorization for POP3 and IMAP accounts.
The comes directly from Mozilla: the Firefox ESR and Thunderbird ESR versions only get security fixes, with full new versions only coming annually. Now, both are on version 153, which appeared in late July.
The main Thunderbird fork is Betterbird.
Waterfox Classic preserved support for the legacy extensions that Firefox Quantum abandoned and continued receiving maintenance for several years. The current Waterfox release, version 6.7, is based on Firefox 153 ESR.
If you want a Firefox-like browser with no AI, a built-in ad-blocker and tree-style tabs, and a slower-moving, more stable release schedule, then Waterfox is worth a look.
The Pale Moon browser forked from Firefox long before even Firefox Quantum; it retains the look and feel of Firefox from version 4 to version 28, which is no longer available in Firefox itself.
Plasmafox was Firefox tweaked to better integrate with the KDE Plasma desktop on Arch Linux, but it fell off its perch after version 88.0.1, five years ago.