Hi @Rahim Molvani ,
When a user changes an item that's subject to retention from a retention policy or a retention label that marks items as a record, or deletes any item subject to retention, the original content is copied to the Preservation Hold library. However, new content isn't copied to the Preservation Hold library the first time it's edited, only when it's deleted.
To store all versions of content in a site, you have to enable document versioning for the document libraries in the site. For more information about versioning, see Enable and configure versioning for a list or library.
For more detail information,please refer to :https://learn.microsoft.com/en-us/sharepoint/governance/ediscovery-and-in-place-holds-in-sharepoint-server#ediscovery-and-in-place-holds-in-sharepoint-server
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