Whether on mobile, tablet, or computer, every time you visit a Google webpage, and you’re logged in, you will see a Notification Widget (the cog icon) next to your profile picture. Get ready to no longer see it, as Google announced that it will be removing it as or March 7, 2019.
Notifications will still be available in the apps for the respective services, namely Google Photos, Hangouts Chat, and Google+ (which will be killed as well come April 2, 2019).
The cog icon, aka said Notification Widget, was used to alert users of pending notifications with a red number corresponding to the number of unseen notifications. Google removing it could indicate that users were not really using it, this being a good opportunity to tidy up things a little bit.