Some connectors (e.g. the PROFINET IO Connector) implement additional specific messages which are not part of the common API spec. Those are defined in an extra asyncapi.yaml (e.g. asyncapi_profinet_io_conn.yaml).
Some connectors are implementing features which would be considered common but are not part of the API definition (e.g. connection status of the SIMATIC S7 Connector). Those are considered experimental and can change in the future once they have been standardized by the common API.