Thanks.
I’ve tried it – din’t work unfortunately.
Also modified it a bit to the following, but not success:
add_filter('woe_get_order_value_direct_debit_iban', "woe_German_decrypt",10,3);
add_filter('woe_get_order_value_direct_debit_bic', "woe_German_decrypt",10,3);
function woe_German_decrypt($value,$order,$field){
include_once WC_GERMANIZED_ABSPATH . 'includes/gateways/direct-debit/class-wc-gzd-gateway-direct-debit.php';
$instance = new WC_GZD_Gateway_Direct_Debit();
return $instance->maybe_decrypt( wc_gzd_get_crud_data( $order, $value ));
}