Hi, @Duchemin, Dominique
Thank you for posting in Microsoft Q&A forum.
We can also check the same logs as the common software update deployments, such as PolicyAgent.log, Scheduler.log, UpdatesDeployment.log, UpdatesHandler.log, CAS.log, ContentTransferManager.log, DataTransferService.log:
There are four ways that admins typically apply updates for Microsoft 365 Apps:
Automatically from the internet
Using Microsoft Configuration Manager
Automatically from an on-premises location
By installing an updated version of Microsoft 365 Apps
https://learn.microsoft.com/en-us/deployoffice/updates/choose-how-manage-updates-microsoft-365-apps
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