Default version limit

Hi ThierryB .  A few years ago, Microsoft set the document library version history defaults to:

• Versioning on
• Versions to keep 500

You can change the number of versions, but you can go no lower than 100 versions.

This applies to both SharePoint Online and OneDrive for Business.

Here's a Microsoft blog post about the new minimum number of versions: New Updates to OneDrive and SharePoint Team Site Versioning - Microsoft Tech Community:

Can I disable versioning?

With these changes, the document library settings page will no longer support the ability to disable versioning or configure it to retain fewer than one hundred versions. Developer APIs, however, will still allow for setting any custom retention count and disabling versioning, however for the reasons stated above this is highly discouraged. 

Here's some Microsoft documentation:

• Versioning in SharePoint | Microsoft Docs
• SharePoint Online document libraries versioning setting changes - SharePoint | Microsoft Docs
• New Updates to OneDrive and SharePoint Team Site Versioning - Microsoft Tech Community