Poor tab management in firefox (both natively and when considering extension options).
Two major deal breakers for me.
1) Tabs do not resize as you open more. So once I hit about 20 tabs the rest scroll off the screen. As someone with ~100 tabs at any time this is completely unmanagable.
2) Lack of any native tab grouping (in a collapsible way) which may have addressed 1 to some degree, and is a needed feature on its own. Extensions do exist but none of them add the feature to the tab bar, all require convoluted UI elements that would be tedious and hacky/workaround at best.
I was pretty commited to making LibreWolf work when I switched to it... but yea there is no amount of getting use to this... i just have way way too many tabs I need.
@freemo @mxtthxw totally agree on the tab sizing. I've finally mastered using my mouse scroll wheel to move along the list but it's not as good as Chromes tab setup.