wp-includes/class-wpdb.php:4148Returns the raw version string of the database server.
string public function db_server_info() { return mysqli_get_server_info( $this->dbh ); }Introduced in 5.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wpdb.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.