I have a really wide monitor, so I end up with wasted space on the sides of most websites, so vertical tabs lets me maximize my vertical space on the screen.

I switched to Omnivore which is open source and has a Firefox plugin.

I have the opposite problem, I used desktop site once, and now for that website it always gives me desktop mode even though I don’t want it to anymore.

I have jerboa installed but it was buggy so I mostly use a browser (Vivaldi)