Things sometimes take multiple clicks to confirm
Upvotes on youtube sometimes glitch out and require you to click a few times
Posting a comment too
Experienced it on other websites so it's not just youtube
- What is your browser and version?
- The problem is possibly not Vivaldi, is possible an extension
- if you have problem with youtube check this link: https://www.youtube.com/html5 and explain if you have all check or not, and try with Flash if you are the same problem
My problem was my mouse, it sometimes double clicks. Has nothing to do with Vivaldi, sorry!
if your mouse have problem, check:
vivaldi://settings/mouse/ (for open, right click -> Open link in new tab)
After I nothing idea, but it's possible it's a plugin or extension,
if not, there is your OS.