How can I get detailed logs for repeated Linode Backup snapshot failures?

The managed Backups service has failed twice consecutively for one of my Linodes. I received an automated support notification, but it does not contain a failure reason, error code, timestamp, or any diagnostic information.
The Linode appears healthy:

• The root filesystem is ext4 and reports a clean state.
• There is plenty of available disk space and free inodes.
• I cannot find any recent filesystem or I/O errors in the kernel journal.
• The node remains online and otherwise works normally.
• The Backups service succeeded on my previous Linode with a comparable workload and file count.
  This Linode contains several million small cache files. I recently reduced that number substantially, but I do not know whether the file count is actually causing the failures or whether the problem is elsewhere.
  Is there any customer-accessible place to view detailed logs or diagnostics for managed backup/snapshot jobs? In particular, I would like to find:
• The exact failure reason and phase of the backup operation
• The backup attempt timestamps
• Any error code or internal job ID
• Whether the failure was caused by file count, duration, filesystem state, storage capacity, or a platform-side issue
• Any documented file-count or duration limits for the Backups service
  If these details are available only internally, what information should I request from Support so they can identify the actual cause instead of relying on trial and error?
  Thanks.