I have been using firefox for a long time, but recently the UI on firefox changed from their simple square look to a childish bubbly one. I dont know how or even if its possibe to revert it back. Looking for suggestions and/or opinions on this change. https://i.imgur.com/Z160vhP.png
You can use Firefox ESR if you want a Long Term Release without the newest features. https://support.mozilla.org/en-US/kb/firefox-esr-release-cycle
Nor for Firefox Dev Edition though
If I understand correctly, Dev Edition is just Firefox Beta with a dedicated profile to not interfere with your main FF browser instance. I guess you could emulate that with ESR too. I don’t know how profiles are really configured.