Why does $wpdb->update corrupt html code and how to fix it?

Question

WordPress

I make a request to update a record in the database:

$wpdb->update( 
        $wpdb->prefix . 'table', // указываем таблицу
        array('url' => $_POST['url'],
            'html_code' => $_POST['html_code'],
            'post_type' => $_POST['post_type'],
            'categ_name' => $categ,
            'by_title' => $header
        ), 
        array( // где 
          'ID' => $_POST['post_id']		
        ), 
        array( '%s' ),
        array( // формат для «где»
          '%d',
          '%s',
          '%d',
          '%s',
          '%s',
        )
      );

The code from the wp_editor form comes to html_code, but, let's say, when you upload an image, after the request, extra \" or just \ appear in the image code - why is this and how to fix it?