SERVER-65948 and SERVER-68202 introduced the changeStreams cluster parameter, which will be used to set the retention policy of change streams in serverless clusters. Although the parameter has now been introduced, the underlying work to make use of the parameter properly is only targeted for 6.2. As a result, the project is guarded behind a feature flag that will remain disabled for the 6.1 release. However, this feature flag is not being checked in getClusterParameter or setClusterParameter, meaning that external users will be able to set and see the value of changeStreams.expireAfterSeconds before it has any meaningful significance. This problem is likely to resurface in the future as additional cluster parameters are added to the server that control feature-flagged behavior.

The long-term solution is to bake feature flags into the IDL definitions of server parameters so that they can be arbitrarily included/excluded from setParameter/setClusterParameter/getParameter/getClusterParameter based on whether the specified feature flag is enabled or not.