Need to know the specific version number. The latest production version is 16.68.0. If you have an older version, click on Help in any of the Microsoft 365 Apps such as Word, etc. and click Check for Updates. Quit all your Microsoft 365 Apps and update to the latest version. If you have a newer version then you are using a preview or beta release.
Did you install Microsoft 365 from the Mac App Store or from Microsoft? It's available from both sources. They both work the same except special volume or standalone licenses only work with the Microsoft installation and not the Mac App Store installation. Both work with 365 subscription logins.
The Microsoft 365 lead engineer, Paul Bowden posted this utility site to help people fix most any problem with 365. It has utilities to reset the 365 Apps or completely remove the software allowing you to re-install it and resolve any corruption.
https://office-reset.com