block editor - Loading template part programatically, inline styles missing

<?php
/**
 * Data provider for block patterns.
 *
 * @package Test
 */

namespace RomArt\DataProviders;

/**
 * BlockPatternsDataProvider class.
 */
class BlockPatternsDataProvider extends DataProviderBase {
    /**
     * Gets the page header block pattern.
     *
     * @return string
     */
    public static function get_page_header_block_pattern(): string {
        $header_pattern_posts = get_posts( [
            'name'       => 'header-pages',
            'post_type'  => 'wp_template_part',
            'numberposts'=> 1,
        ] );

        if ( empty( $header_pattern_posts ) ) {
            return '';
        }

        return do_blocks( get_post_field( 'post_content', $header_pattern_posts[0]->ID ) );
    }

    /**
     * Gets the footer block pattern.
     *
     * @return string
     */
    public static function get_footer_block_pattern(): string {
        $footer_pattern_post = get_posts( [
            'name'       => 'footer-pages',
            'post_type'  => 'wp_template_part',
            'numberposts'=> 1,
        ] );

        if ( empty( $footer_pattern_post ) ) {
            return '';
        }

        return do_blocks( get_post_field( 'post_content', $footer_pattern_post[0]->ID ) );
    }
}

This works fine and it returns template parts, but some styles are missing.

When I use these template parts in the block editor, for example to create a page template, all styles are there. But when I load them programatically like this, some are missing.

I noticed some differences in CSS classes, such as when the foooter is loaded in the page template (block editor), it has class wp-container-core-group-is-layout-15 and it looks good, but when I load it programatically, it has wp-container-core-group-is-layout-10 and looks different