What is the ruling on interest that was neither requested nor specified by the lender, and which the borrower offers when seeking a financial loan for the purpose of trade? And is this interest considered usury (riba)?

A loan is the giving of money to benefit from it, then returning its equivalent without any profit for the lender, because it is not permissible to use a loan as a means of earning profit. If the repayment of interest to the lender is stipulated or customary, then it is forbidden usury (riba). However, if it is a voluntary act from you and without any condition, then there is no harm, and the Prophet, peace and blessings be upon him, praised those who repay debts well.