Theme json causing Error 404 The site could not be found - wordpress

Question

I have created several "fake" pages on my website to display information from another database. I recently adopted the Gutenberg editor blocks in the theme but I run into this problem. If I include the theme.json in the root folder of the domain, the "fake" pages are not displayed and return the 404 error. If I remove the theme.json file, I lose the css styles but the pages work again. Does anyone know how to solve this problem?
add_filter( 'the_posts', 'generate_fake_page', 0);
function generate_fake_page($posts) {
$post = new stdClass;
$post->post_author = 1;
$post->post_name = $url_slug;
$post->guid = home_url() . '/other/';
$post->post_title = 'My fake page';
// content
$post->post_content = $content;
$post->ID = $my_uniq_id;
$post->post_type = 'page';
$post->post_status = 'static';
$post->post_excerpt = '';
$post->comment_status = 'closed';
$post->ping_status = 'open';
$post->comment_count = 0;
$post->post_date = $my_date
$post->post_date_gmt = $my_date;
$posts = NULL;
$posts[] = $post;
// make wpQuery believe this is a real page too
$wp_query->is_page = true;
$wp_query->is_singular = true;
$wp_query->is_home = false;
$wp_query->is_archive = false;
$wp_query->is_category = false;
$wp_query->is_attachment = false;
unset( $wp_query->query[ 'error' ] );
$wp_query->query_vars[ 'error' ] = '';
$wp_query->is_404 = false;
return $posts;
}