Vivaldi is a new modern web browser from Vivaldi Technologies, a company founded by former co-founder and CEO of Opera, Jon Stephenson von Tetzchner. It is available for windows, mac and linux OS. You can download it from vivaldi download page.
It will work mostly well with windows but it will cause some flickering or flashing screen problem in ubuntu and some other linux distributions. For example if you play any youtube video on vivaldi browser it will happen. Mainly the flickering depends on you GPU driver.
1.Update your GPU drivers
First try to update or install your graphics drivers and restart you system.
2.Deactivate the hardware acceleration (Note: This option solves my problem)
Second try to deactive the hardware acceleration feature in vivaldi. To deactivate open your vivaldi browser and type the below code in the vivaldi address bar and hit enter.
Then uncheck the use hardware acceleration when available option. And the restart your browser.
3.If you still facing the issue, go to vivaldi menu->tools->settings and check the Use native window option and restart your browser.
4.Open Vivaldi with –disable-gpu will also solve.Open terminal and in your terminal type the below code and hit the enter key.