Helper class for ACF and Gutenberg. Get blocks fields by passing block_id and post_id.

ACF Gutenberg get block fields

<?php
class BlockHelper
{
    public function getBlockFromPage(string $block_name, int $post_id)
    {
        $post = get_post($post_id);

        if (!$post) return false;
        $blocks = parse_blocks($post->post_content);

        if ($blocks) {
            foreach ($blocks as $block) {
                if($block['blockName'] == $block_name) {
                    return $block['attrs']['data'];
                }
            }
        }

        return false;
    }

    /**
     * Return post id by checking for post instance, second POST param post_id (eg. if ACF ajax preview from Gutenberg), third GET page_id (WP preview)
     * @author Jens Soegaard <jens@jenssogaard.com>
     */
    public function getPostId()
    {
        if (get_the_ID()) return get_the_ID();
        if (isset($_POST['post_id'])) return $_POST['post_id'];
        if (isset($_GET['page_id'])) return $_GET['page_id'];

        return false;
    }
}

usage.php

<?php
	$post_layout = new BlockHelper();
	$post_layout = $post_layout->getBlockFromPage('acf/post-header', get_the_ID()); // name of the block array()
	$post_format = $post_layout['hero_image'];// name of the field