So i am using Discord a lot and i have encountered this problem more than once: you close Discord but the notifications still come even though the icon in the systray is not there. Pretty annoying right?
I found 2 cool things to deal with this:
1 – https://extensions.gnome.org/extension/1031/topicons/ – install topIcons Plus – this will show you the systray at the top and if you close any program from there, it really stays closed.
2 – press “control+q” while having Discord opened. – same result.