When an ad notification pop up appears in Gnome it has a settings button in the notification that takes you to the ad site, exactly the same as clicking just the notification does. Don't know if the notification is meant to have a button but its misleading that its labelled 'Settings' and just takes you to the ad, was expecting to go the brave://rewards page or something. I think the button either needs removing, relabelling, or its action changing

Button actually goes to ad settings
All add notifications - easily reproduced
Brave | 0.63.48 Chromium: 74.0.3729.108聽(Official Build)unknown聽(64-bit)
Revision | daaff52abef89988bf2a26091062160b1482b108-refs/branch-heads/3729@{#901}
OS | Linux
Manjaro Linux with Gnome 3.32.1
Ideally it should open the system notification settings to turn on/off.
Facing the same issue (using ZorinOS) and the ad also does not go away automatically, as it does in windows after ~5 sec.
@jwsp1 ads notification persist for a longer duration this is expected behaviour
Verification passed on
Brave | 0.68.119 Chromium: 76.0.3809.87聽(Official Build)聽beta聽(64-bit)
-- | --
Revision | 111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS | Ubuntu 18.04 LTS
Verified test plan from https://github.com/brave/brave-core/pull/2570
