The earliest recollection of this bug is traced back to PAN-OS 9.1.7 - July 29, 2024. This bug is fixed in PAN-OS versions 9.1.7. Fixed an issue on the firewall where GlobalProtect Clientless VPN portal landing page customization for the navbar_bg_color variable did not take effect. For more information: https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-7-addressed-issues