How to modify the language switcher block to only use the language code instead of its full name?
One possible solution would be to insert this snippet in your .theme file

In this example I am using bartik as a theme.

/**
 * Implements hook_preprocess_HOOK() for block.html.twig.
 */
function bartik_preprocess_block(&amp;$variables) {
  if ($variables['plugin_id'] == 'language_block:language_interface') {
    foreach ($variables['content']['#links'] as $key =&gt; $value) {
      $variables['content']['#links'][$key]['title'] = strtoupper($key);
    }
  }
}


Please, let me know if this solution works for you.

Best regards,

Oleg