Hmm i think we're discussing in two different topics. As i said, i blocked all the notifications (as you can see here https://imgur.com/a/INpzleA) but the little key is still on the top left on my screen and. I mean if you want to work according to the link, to which category (as said on the link) belongs the little key ? Thanks again
Actually, i found a solution just press the VPN status button and set the Importance to "Low: No sound or visual interruption" . The key will disappear (as seen here https://imgur.com/a/bOgkufD ) but i still have this "Android System VPN is activated by Adguard" and i couldn't find how to remove this one though. Thanks !