Using the New Outlook for Mac for personal email and calendar
Hi,
Click the person-shaped profile with the blue dot > Check the accounts linked to that profile > Sign in to the same account using Outlook web > Check for unread messages, including Junk Email and Deleted Items. If none appear online, the blue dot may be stuck in Outlook for Mac.
Quit Outlook completely using Command + Q > Reopen it and check whether the dot disappears.
If it remains, sign in to the affected account through your email provider’s website and check for unread messages there.