Source

File: wp-includes/ms-site.php

function wp_maybe_update_network_site_counts_on_update( $new_site, $old_site = null ) {
	if ( null === $old_site ) {
		wp_maybe_update_network_site_counts( $new_site->network_id );
		return;
	}

	if ( $new_site->network_id != $old_site->network_id ) {
		wp_maybe_update_network_site_counts( $new_site->network_id );
		wp_maybe_update_network_site_counts( $old_site->network_id );
	}
}