I think you had 2016, not 5 user 365.
This is an ongoing problem:
https://yourwindowsguide.com/2026/09/office-2019-deactivated-kb5002907.html
https://support.microsoft.com/servicing/os/microsoft-365/kb5002907-optional-update-for-out-of-date-microsoft-365-apps-installations
Microsoft has received reports of unexpected results on some devices running Office 2016 or Office 2019 after this update is installed. This update was intended to address issues with devices not receiving updates to Microsoft 365 Apps. As part of the repair action applied by this update, some devices were left without functioning versions of Microsoft 365 Apps or Office. To prevent additional devices from being affected, we have paused the rollout of this update. If your device is affected, use the appropriate resolution:
Need more help?
If the issue persists after you complete the appropriate resolution steps, contact Microsoft Support. When you contact support, describe the issue and the steps you have already completed so that we can connect you with the appropriate assistance.