In the following Microsoft Support article for OneDrive Comments and Activity It explicitly says "all the activities that have happened inside your OneDrive. Activities will show for the last 30 days only."
In practice this isn't true, and I don't know how to report this to Microsoft.
Examples: 1. If you delete an item out of a folder you lose all the history except that it was deleted. 2. If you copy items into a folder that doesn't show up in the Details, Activity log.
3. If you stop sharing the folder this log doesn't show that you have stopped sharing a folder with specific people or broken share links.
I would love to see this activity log working as intended so that we could make this useful tracking feature available to our staff and have confidence in the results.