The issue is that you have added a filter specifying 2 arguments to be passed but your function requires 3 arguments.
// 4th parameter is number of args to pass = 2
add_filter('acf/fields/taxonomy/query/key=field_62d02ad58c59f', 'my_acf_fields_taxonomy_query', 10, 2);
// function requires 3 args
function my_acf_fields_taxonomy_query( $args, $field, $post_id ) {
// Order by most used.
$args['parent'] = 0;
return $args;
}