Terminology is still confusing, but I’ll assume you have not run this backup before (or did, then deleted it completely including database and destination). If so, you’ve made it through the backup but all was not running fine (in actuality), and you’re finding out about problems at Verifying backend files, described as:
At the end of each backup job, Duplicati checks the integrity by downloading a few files from the backend. The contents of these file is checked against what Duplicati expects it to be.
I recently asked for opinions, after my terrible experience. Nothing arrived. Maybe yours is feedback?
One difference is that my test was on OneDrive Personal, but yours is OneDrive Business. What exact Storage Type on Destination screen is in use when you get your warnings? I had proposed change.
If you are technical enough to try to compare your “bad” file with my detailed description, that’d be ideal, because I might be able to call the OneDrive expert in, if there’s a (weird) issue multiple people can get.