WP Query : strange behaviour with multiple no-hierarchical tax

Ok, found it, sorry for the noise !…

//fetch the terms of my tax
$terms = wp_get_post_terms( $post->ID, 'tool');
$terms_ids = []; //an array, which can contain several terms
foreach ( $terms as $term ) {
$terms_ids[] = $term->term_id;
}
// Query
$args = array(
'post_type' => 'technical_post',
'posts_per_page' => 4, // How many items to display
'tax_query' => array(
'relation' => 'AND',
array(
'taxonomy' => 'tool',
'field' => 'term_id',
'terms' => array($term->term_id) )
),
);
// Query posts
$tech_query = new wp_query( $args );
// Loop through posts
foreach( $tech_query->posts as $post ) : setup_postdata( $post );
the_title();
// End loop
endforeach;

// Reset post data
wp_reset_postdata();