WordPress Shortcode to JSON-LD relatedLink from current category

wpshortcode.php

// Add Shortcode
function jsonlink( $atts ) {

	// Attributes
	$atts = shortcode_atts(
		array(
			'numberposts' => '',
		),
		$atts,
		'relatedLink'
	);

	$related = new WP_Query(
	    array(
	        'category__in'   => wp_get_post_categories( $post->ID ),
	        'posts_per_page' => $atts,
	        'post__not_in'   => array( $post->ID )
	    )
	);
	
	if( $related->have_posts() ) { 
	    while( $related->have_posts() ) { 
	        $related->the_post(); 
	        echo "relatedLink: [". json_encode($query->get_post_permalink() ."]";
	    }
	    wp_reset_postdata();
	}

}
add_shortcode( 'relatedLink', 'jsonlink' );

Usage

[realtedLink numberposts=5]

Bugs

Line #24 echo "relatedLink: [". json_encode($query->get_post_permalink() ."]";
I'm not good at writing PHP.

Expected Outcome

"relatedLink": [ "https://example.com/category-slug/post-name1", "https://example.com/category-slug/post-name2", "https://example.com/category-slug/post-name3" ],