So far MongooseIM has been using the internal Mnesia database to replicate the in-memory data between cluster nodes.
Now there is an option to use CETS instead.
Mnesia is still used by default, so you don't need to change your configuration file.
If you want to switch to CETS, see
Transition to New CLI Commands
Legacy CLI commands previously marked as deprecated have now been removed. The users are encouraged to explore the new GraphQL-based CLI. It is recommended to transition to the new CLI commands prior to the next system upgrade. The configuration options
services.service_admin_extra related to the legacy CLI were also removed. You need to remove them from your configuration file unless you have already done so.