Google Publisher Toolbar is going away and will no longer be available for use from May 2020 and shall be removed from the Chrome web store.
The toolbar browser extension is used to access Adsense data. It helps to view data on your AdSense, Ad Exchange, and DoubleClick for Publisher’s ads and accounts, and block unsuitable ads on your site. All features from Google Publisher Toolbar will be accessible from the Adsense interface.
Google is very well known for often making changes to its line of products and apps. You can also use the below important links to manage your Adsense.