Take a look at this page: https://www.advancedcustomfields.com/resources/image/
I’d set the return value of the custom image field to Image URL and put something like this in your template:
<?php
$taxonomy_image_src = get_field('image_indicateur_confiance');
if ($taxonomy_image_src) { ?>
<img src = "<?php echo $taxonomy_image_src;?>">
<?php } ?>
