That's because in Islam it is a sin to extract interest, and the rate of inflation is high with the Turkish Lira, so this is a way to keep it fair for those among the last to get the loan.
由於伊斯蘭教義中拿人利息是罪孽，但土耳其通貨膨脹率高，就用這種方式來避免晚收會款的人吃虧。