Hi @Roger Roger
You could go to Microsoft 365 admin center > Compliance to check audit log by selecting related date and time range, deleted file activity, and OneDrive site url:
Then you will get the audit log result as shown below:
In addition, please check if there are any Labels or Retention policies under Information governance that would delete files automatically:
Retention label:
Retention policy:
If the any of the above matches to the situation, please turn them off to prevent this in future.
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