systemd-networkd autoupdates remove ip routes added by guest-agent causing NLB targets to fail

[char8]

• systemd-networkd autoupdated to 252.39-1~deb12u2
• this caused the guest-agent added routes to the local routing table to get removed
• NLBs targeting the impacted VMs started failing healthchecks and couldn't deliver traffic to the VMs
• a manual restart of google-guest-agent.service was required to fix networking

guest-agent should either chain a restart from networkd or actively reconcile routes?

[drewhli]

Can you give me the version of the guest agent that you were running when you encountered the issue? As for the OS/image, it seems to be Debian 12, looking at the systemd-networkd version, but just to be sure, can you confirm the image on which you encountered this issue as well?