Prepopulate CPTs with a reusable block and convert it to a regular block automatically

cpt-block-prepopulate.php

function convert_reusable_block_to_regular_block($data, $postarr) {
    // Check if it's a new custom post type
    if ($data['post_type'] === 'your_custom_post_type' && $data['post_status'] === 'auto-draft') {
        $reusable_block_post = get_page_by_title('your_reusable_block_name', OBJECT, 'wp_block');

        // Check if the reusable block exists
        if ($reusable_block_post !== null) {
            $reusable_block_content = $reusable_block_post->post_content;

            // Convert the reusable block into a regular block
            $data['post_content'] = $reusable_block_content;
            $data['post_status'] = 'draft';

            // Remove the reusable block reference
            $data['post_name'] = '';

            // Update the post title if needed
            // $data['post_title'] = 'Your New Post Title';
        }
    }
    return $data;
}
add_filter('wp_insert_post_data', 'convert_reusable_block_to_regular_block', 10, 2);