Argo CD v3's own CRDs (applications, applicationsets, appprojects) embed large schemas that exceed the 256KiB last-applied-configuration annotation a client-side apply writes — the same reason cert-manager and external-secrets already use this. Without it the upgrade sync fails on the CRDs rather than on anything in the release. ServerSideDiff comes with it for the same reason as the other three, and becomes belt-and-braces once the upgraded Argo CD's schema matches the cluster. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LEsTefWWifp4ikvhHF5s6N