Yes, actually it's illegal to differentiate the price based on destination country, a SEPA transfer is a SEPA transfer. But as .de uses the euro as its currency

Yes, actually it's illegal to differentiate the price based on destination country, a SEPA transfer is a SEPA transfer. But as .de uses the euro as its currency, all in-country transfers are SEPA transfer, which I suppose isn't the case for Złoty transfers within Poland, thus allowing for differentiated prices?