The earliest recollection of this bug is traced back to PAN-OS 9.1.11 - July 29, 2024.
This bug is fixed in PAN-OS versions 9.1.11.
Fixed an issue where the Certification Revocation List (CRL) in Distinguished Encoding Rules (DER) format incorrectly returned errors despite being able to successfully pull the CRL to verify that the syslog server certificate was still valid.
For more information:
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-11-addressed-issues