What
When a plugin's stored options are deleted, Claude Code now checks afterwards that the deletion worked. It clears pluginConfigs (the answers you gave a plugin's configuration dialog) from your user settings. It also clears pluginSecrets from secure storage, the protected place where secrets such as keys are kept. Then it reads both back. If something went wrong, it reports one of these reasons:
settings_unreadablesettings_write_failedsecrets_write_failedsecrets_unreadablesecrets_remain
Why
Before, a failed cleanup could pass silently and leave a removed plugin's settings or secrets on your machine. Now a failure is named, so you learn when something may still be stored.