A migration to remove ALL links from images on all wordpress posts

remove_linked_images.php

/** 
 *  A migration to remove ALL links from images on all wordpress posts
 *  Based on https://gist.github.com/cfxd/219f083465bb5b93fac8#file-remove_wp_selfies-php
**/
function remove_linked_images() {
  $all_ids = new WP_Query(array(
    'post_type'      => array('post'), // feel free to add custom post types here if necessary
    'posts_per_page' => -1,
    'post_status'    => 'publish',
    'fields'         => 'ids'
  ));
  foreach($all_ids->posts as $id) {
    $current_post     = get_post($id);
    $current_content  = $current_post->post_content;
    preg_match_all('/(<a.*?>)(<img.*?>)(<\/a>)/', $current_content, $matches);

    $linked_images = $matches[0];

    if (count($linked_images) > 0) {
      $content_replaced = $current_content;
      $wp_images = $matches[2];

      foreach ( $linked_images as $key => $replace_str) {
        $content_replaced = str_replace($replace_str, $wp_images[$key], $content_replaced);
      }

      wp_update_post(array(
        'ID'           => $id,
        'post_content' => $content_replaced
      ));
    }
  }
}
add_action('admin_init', 'remove_linked_images');