Reverse query relationship acf field

gistfile1.txt

//obtain pages or post who added a relationship item - Reverse relationship posts

$tasks = get_posts(array(
	'post_type' => 'task',
	'meta_query' => array(
		array(
			'key' => 'task_parents', // name of custom field
			'value' => '"' . get_the_ID() . '"', // matches exaclty "123", not just 123. This prevents a match for "1234"
			'compare' => 'LIKE'
		)
	)
));