Implementation of JDBC DataSource in MySQL Connector/J 8
The driver has com.mysql.cj.jdbc.MysqlDataSource (there is also a ConnectionPoolDataSource and an XADataSource implementation). The actual implementation of MysqlDataSource uses the JDBC driver directly, similar to what DriverManager would do.
The MySQL Connector/J hardly mentions data sources. In fact, the only reference I could find to MysqlDataSource was in Changes in the Connector/J API. I'm not sure if it is a conscious choice by the MySQL documentation team, but it usually makes little sense to use MysqlDataSource directly in your code (it doesn't provide connection pooling), and MysqlConnectionPoolDataSource and MysqlXADataSource are not for direct usage nor are they a connection pool (instead they serve as a factory for connections for a Java EE data source that provides connection pooling and/or distributed transactions).
A lot ways of using JDBC involves using third-party data sources providing a connection pool (eg HikariCP, DBCP, c3p0), and those usually use DriverManager directly (though some also allow you to provide a data source implementation), or through a data source of a JavaEE/JakartaEE application server. It is usually better to use those than to rely on the data source implementation of a driver.