Hello @CW , Thanks for the question and using MS Q&A platform. As we understand the ask here is to find out if there is any setting in the portal which will delete the files, please do let us know if it's not accurate.
I will start the check at "Data protection option " on the portal.
Thanks Himanshu
Please "Accept as Answer" and Upvote if the answer provided is useful, so that you can help others in the community looking for remediation for similar issues.