Toggling on Godot game causes an NS_ERROR_DOM_COEP_FAILED on firefox

After discovering additional settings, 
Toggling on Godot game additional setting caused an NS_ERROR_DOM_COEP_FAILED on firefox of my PC and mobile.
This issue does not exist if I am not logged in.
Currently have turned it off to allow my game to be played by account users.
How necessary is this setting? And if it is, how to avoid this error.