You’re welcome, and I’m glad you tracked it down. Often it’s not clear what happened. This time we at least can end with an assumption that Minio sent something down that Duplicati rejected, maybe a truncated file, however an error such as cp reported would have been nicer. Minio uses S3 and for that Duplicati uses an Amazon library, so tracking it through all that to figure out how/if error reporting took place is beyond me…
If you like, you could check if Duplicati.CommandLine.BackendTool.exe gets a partial file, an error, or other.
This leaves you the awkward question of what to do with the drive. Internal hard-drive defect management describes how bad sectors get remapped. Sometimes vendors also have special tools for their own drives.
smartctl can supply generic information that might help to determine if any additional problems are arising.
How to force a remap of sectors reported in S.M.A.R.T C5 (Current Pending Sector Count)? suggests how sector remapping can be forced by an overwrite. That file is seemingly lost, and you can (if you like) get an enhanced view of how where the error starts by wc -c or redirect into dd bs=1 to see what count you get.
There’s no way to rebuild the lost dblock, but you can use the affected command to see what was affected, then delete the bad dblock and run list-broken-files and purge-broken-files. How to list / purge broken files
A fresh backup (e.g. export/import/modify) would also work if old versions on this backup are not important.