Hide tags from display if there is only one post in the taxonomy.

my_get_the_terms.php

<?php
/**
 * Hide tags from display if there is only one post in the taxonomy.
 *
 */
function my_get_the_terms( $terms, $post_id, $taxonomy ) {
	if ( $taxonomy === 'post_tag' ) {
		foreach( $terms as $key => $term ) {
			if ( $term->count < 2 ) {
				unset( $terms[ $key ] );
			}
		}
	}
	return $terms;
}
add_filter( 'get_the_terms', 'my_get_the_terms', 10, 3 );