While I am generally satisfied with my Norton subscription, I am getting really tired of being unexpectedly pulled out of an on-line game by some pop-up message that is trying to sell me more Norton product.
Go to <user settings>, <administrative settings>, <silent mode>, <user-specified programs> (last item in the list). You can specify executables to start silent mode. For example, I set the Norton executable but you could use the Steam executable. This way you don't have to keep remembering to do it...
If you do use the Norton executable, remember to reset it after any updates to Norton because it includes the version number in the folder name.
This workaround has been working for me since September 2022.
I have less than 2 months of subscription left and will not be renewing purely because of the popups. A shame because it is otherwise a decent product.
All: Silent mode should be detected automatically. I game on Steam, run a gamer server there as well. Steam always goes into "Full Screen' detection. Maybe silent mode detection is the key?
Have you tried turning on Silent Mode before starting your game(s)? Right click on the Norton icon in the system tray and click on Turn on Silent Mode.