Ok solved it alone, sharing here if ever someone needs it.
function icon_avant_term( $title, $term, $field, $post_id ) {
if(is_admin() && ("produits" == get_post_type($post_id)) ){
$taxo = $title;
$image = get_field('icone_liste_plus', $term);
$title = '<img src="'.$image['url'].'" /> ' . $taxo;
return $title;
}
}
add_filter('acf/fields/taxonomy/result/name=point_cle_produit_icon', 'icon_avant_term', 10, 4);