You need to use the correct term id to get fields from a term and not the term object. I don’t know why one works and the other does not, but according to the ACF documentation using the term object is not something that supported
<?php
// Get vars for taxonomy custom Fields
$queried_object = get_queried_object();
$taxonomy = $queried_object->taxonomy;
$term_id = $queried_object->term_id;
$post_id = $taxonomy.'_'.$term_id;
?>
<div class="col-md-6 mb-">
<!-- desctription -->
<?php
echo get_field('beschreibung', $post_id);
?>
