The earliest recollection of this bug is traced back to PAN-OS 9.1.2 - July 29, 2024.
This bug is fixed in PAN-OS versions 9.1.2.
Fixed an issue where the CPU for a process ( ikemgr ) spiked when third-party VPN clients connected to the GlobalProtect gateway with more than three DNS servers configured.
For more information:
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-2-addressed-issues