https://www.bleepingcomputer.com/news/microsoft/microsoft-is-showing-ads-for-microsoft-365-in-office-2021/

Microsoft is showing ads for Microsoft 365 Family subscriptions to its Office 2021 customers, offering them discounts of over $28 to get a 3-month Family plan subscription.

Several users have reported seeing these ads this week, starting on August 10, with Lee Holmes, a Principal Security Architect at Microsoft Azure Security, also sharing today a screenshot showing the ad displayed as an alert bar under the Office menu.