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.
( VM-Series firewalls deployed in Amazon Web Services (AWS) instance types M5 and C5 only ) Fixed an issue where a Panorama Virtual Appliance in an HA configuration entered a suspended state due to a virtual machine (VM) memory size mismatch.
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