The change only seems to apply within the Abgeltungsteuer. But this type of tax can easily be avoided by use of the Günstigerprüfung. Mark the corresponding box in your tax forms and you'll pay either Abgeltungsteuer or your personalized tax rate on all your income, whichever is less. And since the rules for the latter haven't changed, losses from derivatives can then be deducted as before. Also a broker outside Germany won't automatically transfer Abgeltungsteuer, it's your own responsibility to take care of taxes after the year, enabling you to pay the lesser rate.
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To avoid that altogether, have a company (anywhere) to trade through as the Abgeltungsteuer only applies to natural persons. Or alternatively, trade as a natural person but move your legal residence outside Germany.