Continuous "Notify.app" Popup on MacBook Pro

For the past month or so, a few times each minute I get a popup on my Mac that says "Do you want the application "Notify.app" to accept incoming network connections? Clicking deny may limit the applications behavior. This setting can be changed in the Firewall pane of Security Preferences." It very quickly flashes onto my screen, then disappears before I can click Accept or Deny. It's really irritating and interrupts anything I am doing on my computer, and as an artist it makes it difficult to use programs I need such as Photoshop and Illustrator.

I have checked my Firewall preferences, but I do not want to allow the incoming connections as this is the Mac Help page for the popup. I do not know what it is referring to, but I do not want outside computers connecting to any apps on my computer.

I have also searched my computer for an app called "Notify," in case it was something I downloaded at some point. There's nothing. I don't really know what to do without allowing these connections when I don't know what app is causing the pop-up. Has anyone else encountered something like this? It's really driving me insane