Is it permissible to repay the loan amount at half the value of the current agreed-upon apartment (EGP 400,0), or must only the borrowed amount (EGP 250,0) be repaid?

It is not permissible to stipulate an increase on a loan, and any stipulated increase is usury (riba), the prohibition of which is unanimously agreed upon. A loan is repaid with its equivalent. However, if the currency depreciates by one-third or more, then the lender must be compensated for this loss in their wealth. The compensation is determined by mutual agreement between the two parties to divide the difference between the original value of the money and its value after the currency depreciation.