I used them when they were released a while ago for the nightly version of Firefox, and actually in the stable channel we are in Firefox 130 and still no vertical tabs, does anyone know an aproximate version when they will be available for the stable channel?
You can enable them right now by setting
sidebar.verticalTabs = truein about:configIts very basic right now. It literally just lists the tabs. You cant group them or anything.
Still, its nice to see it actually being implemented, and Im sure itll get better over time.