Assuming it's not an ad - just a notification from Anandtech ...
In Firefox (if you use Firefox), go to "about: preferences#content" and hit the Choose button in the Notifications section. If you see a site(s) listed as blocked, it means you once answered "no" when Firefox asked you whether or not to let this site send notifications.
Apparently, you answered "yes" to the question and hence the popup. No idea how to reset if you answered "yes." I don't see how to add a site manually to the block list, so I guess you would have to block ALL notifications ... i.e. Do Not Disturb setting.
Hope that's clear. That's how Firefox works, not sure about other browsers. Maybe others know some hacks.