It should be fixed in https://blogs.opera.com/desktop/2020/03/opera-68-0-3616-0-developer-update/ at least. Might take a bit before the fix reaches stable.

I don't think it even needs to be an option. Opera should just do as other browsers and do the switch on keydown like you suggest.

@krista personally, I am against. Remember that Android is not Windows. If 1 click on the tab in Opera Windows scrolls the page up (and the second one to the previous place) then personally I would prefer that a double click would scroll the page down.