It seems like you are experiencing some graphics issues with your AMD RX570 8GB graphics card. Specifically, you are seeing flashes, twitches, and glitches while browsing, but not when the GPU is under load in games.
Based on your description, it is possible that the issue could be related to low GPU frequency switching. One potential solution you could try is to increase the minimum frequency of the GPU processor. Here are some steps you can take to do this:
Download and install the latest drivers: Make sure you have the latest drivers installed for your graphics card.
Open the Radeon Settings: Right-click on your desktop and select "Radeon Settings" from the context menu.
Go to the "Gaming" tab: Click on the "Gaming" tab in the Radeon Settings window.
Select your browser: Under "Gaming," select your browser from the list of applications.
Click "Profile OverDrive": Click on "Profile OverDrive" and enable "Manual Tuning."
Increase the minimum frequency: Increase the minimum frequency of the GPU processor using the slider in the "GPU Frequency" section.
Apply the changes: Once you have made your changes, click "Apply" to save them.
Restart your browser: Close and restart your browser to see if the issue has been resolved.