Is it considered usury if a debtor repays an amount in dinars for a previous loan in euros, calculated at the current exchange rate, which results in an increase of 2,000 dinars over the original amount in its equivalent value at that time?

It is not permissible to stipulate repayment of the loan in a currency different from the loan's currency, because it is a currency exchange (sarf), and currency exchange requires immediate possession in the contracting session. However, if the repayment date is due, and the borrower wishes to repay in another currency and possession occurs, there is no objection; because exchanging currency for what is owed after the due date is like exchanging currency for what is already possessed.