I use Vivaldi day to day, mostly because of tab stacks, but it crashes fairly often and loses my tabs in the process (I can always restore them from its trash though). I just got the new release, and discovered another bug: If you're on tab A and right-click on a tab stack B, and click "pin tab stack", it pins your current tab, rather than the stack you clicked on.

I want to like Vivaldi, but how do these things pass QA?