It sounds like you are referring to the web push notifications feature, which is something that any website can use. You can find that setting in the '''Privacy & Security''' section of the Firefox settings page. If you scroll down to '''Permissions''', you will see '''Notifications'''. You will have the option to temporarily pause notifications until you restart Firefox. If you press the '''Settings...''' button, you will have the option to remove notifications from specific websites or all websites, as well as stop websites from asking for permission to send notifications in the future. More information about this feature can be found on the [[Web Push notifications in Firefox]] page. Hope this helps.