acf.php

<?php

/**
     * Get the header BG color
     *
     * @return string
     */
    public function blogColor()
    {
        $term = get_queried_object();
        // What object type is?
        $class_type = get_class($term);
        // If is the taxonomy archive and the term is W
        if (is_archive() && 'WP_Term' === $class_type) {
          $has_custom_header = get_field('tax_custom_header', $term);
          if ($has_custom_header) {
              return get_field('tax_custom_header', $term);
          }
          return get_field('tax_header_color', 'options');
        }
        return false;
    }