I had a problem with this for a while and I didn't find any fix for this problem on Manjaro forum, so I created this post to help people with this problem.
(Also I heard some people because of this problem changed distro to some other.)
Steps to fix the problem:
Open nvidia-settings (NVIDIA X Server Settings)
- You can open NVIDIA X Server Settings with typing "nvidia-settings" into the terminal and pressing Enter/Return key
- You can open it with your Application Menu, search "NVIDIA" and it should show application "NVIDIA X Server Settings", click on it
Find option with string "OpenGL Settings" and click it
Uncheck/unclick/disable option "Allow Flipping"
Now when you open OBS and add into the current scene "Screen Capture" it won't flicker anymore with OpenGL rendering.