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
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.