Here is the link: https://forum.obsidian.md/t/obsidian-sync-server-command-definitions/20436/2?u=cawlinteffid. (The restriction on linking is an anti-spam measure for new users, which I’ve now lifted from your account.) The Help page gives a similar definition: Status icon and messages - Obsidian Help (and links to more info about how Sync handles conflicts: Troubleshoot Obsidian Sync - Obsidian Help).
Since there are separate log messages about conflicting changes, I think we can conclude that when changes are rejected there is no conflict — it’s just an older version of the file. But I agree the definition isn’t clear enough and should say that explicitly if that’s the case.