What is the ruling on transferring money to another country at an exchange rate different from the actual rate, with the transferor receiving the difference as his percentage, and then the received amount being transferred to the other country, with the possibility of profit or loss when it is exchanged there?

Exchanging currencies (money exchange) is not permissible শরعًا unless there is mutual possession (قبض) in the contract session. Otherwise, it falls into the prohibited interest of delay (riba al-nasī'ah). If the two parties separate before mutual possession, the exchange is invalid. It is permissible for the transferor to take a known fee for performing the transfer. If the currencies differ, it is permissible to sell some of them for others at any price agreed upon by both parties, provided there is mutual possession in the session.