Vertical tabs made a lot of headlines when they hit nightly months ago and they were a bit jank, never quite feeling like they're part of the browser. After updating to 133.0 though, turning on the sidebar revamp (sidebar.revamp) and vertical tabs (sidebar.verticalTabs) in about:config now work so well!
There's no blank space hovering between the address bar and top of the window, tab previews work well on hover. Finally I can ditch Sidebery and it's pulled me back over from flirting with Zen and I'm using this setup full time now <3
By extensions to you mean the tabs from other devices and history icons?
Otherwise that's really strange behaviour, which extensions are they? Maybe it's some other userchrome.css modifications you've made?
Nope. It decided to place "Simple Tab Groups" and "Video DownloadHelper" onto the tabs bar, on its own. Apparently in the tab bar settings, there's a place to specify it, but it doesn't appear to be active.
A piefed screenshot in the wild. Have an upvote from me. Also, thanks for the info.