SOLVED
This was what I was looking for and it works like a charm.
function my_query_args($query_args, $grid_name) {
$term_list = get_the_terms( get_the_ID(), 'category' )[0]->slug;
if ($grid_name == 'JTS-SINGLE') {
$query_args['tax_query'] = array(
array(
'taxonomy' => 'category',
'field' => 'slug',
'terms' => array( $term_list ),
),
);
}
return $query_args;
}
add_filter('tg_wp_query_args', 'my_query_args', 10, 2);