The restore fails immediately with the following error: Index was outside the bounds of the array

Support
17

No, the error is in the new restore flow.
It happens if you run more than one restore without restarting Duplicati.
The workaround is using legacy-restore as @triatic mentions.

You can also update to the latest beta release as @ts678 suggests:
Release: 2.2.1.0 (Beta) 2026-03-05