Return Flat Terms with Levels from Shortcode [jet_post_terms tax="your-taxonomy" lvl="2"]

gistfile1.txt

add_shortcode( 'jet_post_terms', function( $atts = array() ) {
	$atts = shortcode_atts( array(
		'tax' => '',
		'lvl' => ''
	), $atts, 'jet_post_terms' );

	$post_id = get_the_ID();

	if ( empty( $atts['tax'] ) ) {
		return;
	}
	$lvl = absint($atts['lvl']);
	$result = array();
	$terms = wp_get_post_terms( $post_id, $atts['tax'], array( 'orderby' => 'parent' ) );

	if ( ! empty( $terms ) ) {
		foreach ( $terms as $term ) {
			$ancestors = get_ancestors( $term->term_id, $atts['tax'] );
            $term->ancestors = $ancestors; 
            $term->depth = count( $ancestors ) ;
            if($term->depth === $lvl)
			{
				$result[] = $term->name;
			}
		}
	}
	return implode(' ', $result );
} );