Hmm based on the minimal information my guess on what you are seeing are Web Push Notifications on bottom right corner of Firefox window from websites you have allowed to send you notifications from. Unfortunately instead of sending you information on useful things it may just be things like junk, spam or fake virus alerts. You can revoke these sites from sending you notifications. https://support.mozilla.org/en-US/kb/push-notifications-firefox https://support.mozilla.org/en-US/kb/push-notifications-firefox#w_how-do-i-revoke-web-push-permissions-for-a-specific-site