If I'm on a page that has web notifications (like Slack or others), Firefox asks me if I want to enable them. However, my choices are "Yes" or "Ignore for now". The problem is, if I select "Ignore", every time there is a notification it asks me again. This is incredibly annoying.
How do I disable this completely? (I would accept disabling this feature entirely if that's easiest.)
Go into about:config and set dom.webnotifications.enabled to false
You can also disable this on a per-site basis by right-clicking somewhere in a blank spot of the site (or pressing Ctrl-I on Windows or Cmd-I on Mac) and then selecting "View Page Info" from the opening menu. This opens a window with a "Permissions" tab. Scroll down until you see "Receive Notifications", uncheck "Use Default" then select "Block."