The config.placementHistory contains a log of which shards stored data of user collections/databases throughout the time. Its consistency state and schema versioning is described by a couple of special documents (called "placement history initialization markers"), which causes a sub-optimal handling of change stream resources when missing or stale.

Such a situation may be manually corrected  today through the invocation of the resetPlacementHistory command - but it should be automatically handled as part of the config server initialization for proper user experience.