BYOAI is usually framed as shadow IT with a better user experience. Someone has a question, a deadline, or a document that needs improving. A public AI tool is one browser tab away. The risk is real, but the human need is real too.
Archiving a SharePoint site is a change to access, ownership, recovery, and compliance. Storage cost matters, but it is the last question I ask, not the first.
For each site, document the business purpose, accountable owner, last meaningful activity, external sharing, sensitivity and retention state, eDiscovery considerations, expected retrieval time, and future disposition date. “No recent edits” is a useful signal. It is not an archival decision by itself.
An unlicensed or inactive OneDrive is not automatically disposable. It can contain project evidence, personal working files required for a case, or content subject to retention. “Orphaned” should be a conclusion from evidence, not a label created by a storage report.
Large files are visible. Retention side effects often are not. That is why a storage incident can become a compliance incident when somebody responds by changing a policy before understanding what is preserving the content.
When SharePoint or OneDrive content is retained, Microsoft can preserve the original version in the Preservation Hold library after a user edits or deletes it. The user may see a file disappear while the tenant still retains a copy. Microsoft explains the workload-specific behaviour in retention for SharePoint and OneDrive.