Previously there was a checkbox to toggle the title bar of firefox on the "Customise Toolbar..." page.
As you can see on my screenshot, this checkbox is no longer there.
Is that a bug i should report or did the checkbox move somewhere else ?
BTW, i'm running Firefox 115.0.2 for ubuntu.
if you need to do something more fancy with the look of firefox (e.g. having url bar in the titlebar) look up styling with userChrome.css
currently im using it to not have duplicated tabs at top when using vertical tabs extension