What is the responsibility of someone who bought a stolen car and sold it to another, then it became clear that it was stolen and confiscated? And is he obligated to compensate the one he sold it to, or the one who sold it to him?

If it is proven that the broker was negligent in the buying and selling, then he guarantees the price of the car purchased by the questioner, just as he guarantees the price to the one who bought the stolen car from him. The broker can then claim the price from the swindler who sold him both cars. The determination of negligence is referred to the prevailing custom in this type of transaction.