[all variants] Chrome 48-49, Opera 36-37 and Chromium: Black Screen Issue

There is a black screen about the size of the calculator window in center left of browsers window (always there) for about 2 seconds. Most of the time when I open them or after visiting some web pages. Also in Windows 10.

Is it a bug in the Chromium architecture, is there a bug? All I know is that it was not there before and there is no relation between the background color and this aoying issue.

Not present in FF nor in Brave 0.83 or in Tor browser. Until further clarification will be using FF only.

Google Chrome Stable extensions:
Discoect, Ad Block, Browsec, Click and Clean (the red one, the right click one)
Opera Developer extensions:

Discoect, Ghostery, Ad Block, Browsec, Close and Clean.

I’m using the same extensions in FF and in Tor that does not need Browsec.