If your Office is stuck in "Mondo 2016" mode and you have a genuine license for another version (like Microsoft 365), you can often fix it by following these steps from Microsoft Support : Microsoft Office Mondo? - Microsoft Q&A
It essentially contains the "everything" package—including features from Pro Plus, Visio, and Project. product key microsoft office mondo 2016
If your Microsoft 365 is incorrectly showing as Mondo, you must reset the activation state: If your Office is stuck in "Mondo 2016"