print custom image field for taxonomy page (page--taxonomy.html.twig) template
Only entities from type node are loaded in the page template by default. If you want this for other entity types you have to add custom code to page preprocess:

function mytheme_preprocess_page(&amp;$variables) {
  if (\Drupal::routeMatch()-&gt;getRouteName() == 'entity.taxonomy_term.canonical') {
    $term = \Drupal::routeMatch()-&gt;getParameter('taxonomy_term');
    $variables['term'] = $term;
  }
}


Then you can access the fields from the term in page--taxonomy.html.twig:

{{ file_url(term.field_image.entity.uri.value) }}