Comment by DaSHacka

That's almost exactly describing Librewolf, though it adds a ton of privacy 'hardening' features out-of-the-box, which can be a positive or negative depending on who you ask.

I personally use Librewolf with the Lepton (Photon style) UI[0], which replicates the previous UI style Firefox used a couple years ago, with small square tabs and condensed menus, before the current pseudo-tabletified abomination.

Of course, if you like the current UI—you'd literally be the first person I've met to like it—you can just use librewolf stock and it doesn't apply any changes to the standard Firefix UI.

[0] https://github.com/black7375/Firefox-UI-Fix