Switching tabs doesn't work like you would expect in Opera for example. The order of tabs gets shuffled randomly. It's completely broken. I downgraded to a version where it had worked, stuck with that for a while. When I complained about it people usually say "just use it like chrome where you can't switch tabs properly anyway lol". It was reported with the precise version that broke it. Vivaldi team asked maybe twice on social media, but then it was just tumbleweeds. It's 100% reproducible with a clean install, on both windows and osx. I gave up and preach for people to just stay away from that browser.