@barbudo2005 Yeah, it's not my best sentence 😅 and there's also a bigger flaw in my previous explanations 😓.
I meant that even if I have that option unticked I still see the Title bar. That setting it's not enough to actually hide the title bar.
The other (bigger) problem: I left out that the other condition is having both Address bar and Title bar at the bottom. With both those bars at the bottom Vivaldi keeps the Title bar at the top.
You can see it in the image, the rightmost portion.
I tend to be verbose, so before posting I simplified my original text, evidently a bit too much. I'll make it clearer with an edit.