Is it permissible to purchase an apartment and pay a portion of its price to the bank that gave its original owner an interest-based loan?

There is no objection to buying a house, but it is forbidden to act as an intermediary in paying the usurious increase to the bank. Pay the installments to the homeowner so that he can pay them to the bank, and avoid direct dealings with the usurious bank. If the homeowner deals in usury and has not repented, it is better not to buy from him.