The earliest recollection of this bug is traced back to PAN-OS 9.1.5 - July 29, 2024.
This bug is fixed in PAN-OS versions 9.1.5.
Fixed an issue where the CLI command Show config running following the CLI command set cli op-command-xml-output on produces an unreadable output.
For more information:
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-5-addressed-issues