As a developer of OCPBUGS, I need:

• Prevent the arbiter and control-plane machine-config pools from restarting nodes at the same time.
• Avoid quorum loss during MCO reboot and upgrade events.

The core issue is that the sync logic happens per-pool, but it needs to handle arbiter nodes as a special case.
https://github.com/openshift/machine-config-operator/blob/747fddc7df5fe50e1f8c568dd9fc5cef47866b5b/pkg/controller/node/node_controller.go#L1076

Impact Notes

• This doesn't actually block the upgrade, but it does introduce temporary quorum loss as the node reboots.

Acceptance Criteria

• A patch is merged into MCO
• A test is merged into CI that verifies that MCO guards against this
• The test is used to verify the bug
• Documentation is updated with a known issue that explains how to work around this

Supporting Documents
MCO MaxUnavailable Docs

Issue synthesized with help from gemini Engineering Jira Buddy gem