No, I don’t. But in my experience with Duplicati the rate of backups that end up damaged is very high, and this is not normal for a end user.
You gave nearly ten approaches, but the only one that I can easily follow is to avoid upload throttle option. Unfortunately, if I have well understood, once the damage is done, deleting such option doesn’t solve the issue.
The other hints are out of my reach, mainly because the time. I have a normal life with limited (even cognitive) resources, and I don’t understand a lot about logs, exadecimal editors, and how to identify a damaged file among thousands.
So, the simplest thing a user lke me can do is to delete a backup and start a new one. As long as a new damage occurs.
This is my sad truth.