See https://github.com/apache/camel-kafka-connector/blob/master/docs/modules/ROOT/pages/connectors/camel-sql-kafka-source-connector.adoc
There are 2 different configs for datasource: camel.source.endpoint.dataSource, camel.component.sql.dataSource.
I had to set the component.sql one because the other one didn't work for me, this is really confusing for the users.