Greenshift Visibility Block filtering via PHP conditions

<?php
add_filter('render_block', 'custom_visibility_conditions_check', 11, 2);

// Don't forget to specify block ID and the CPT slugs in $allowed_post_types
function custom_visibility_conditions_check($block_content, $block){
    if(isset($block['attrs']['id']) && $block['attrs']['id'] == 'gsbp-xxxxxxx') {
        $allowed_post_types = array('books', 'movies');

        if(is_singular($allowed_post_types)){
            return $block_content;
        } else {
            return '';
        }
    }
    return $block_content;
}