For example, everyone buys bonds, and the interest earned by buying Australian bonds is more and more than that earned by buying American bonds. The spread is the interest difference.

This has no direct impact on the foreign exchange rate. However, in the case of expanding bond interest, more funds will flow into Australia in the short term, forming hot money to earn spreads, making the demand for the Australian dollar in the foreign exchange market more than the US dollar, and the price of the Australian dollar against the US dollar will rise. Moreover, debt interest often reflects a country's financial situation and macro-control.

My humble opinion, welcome to discuss.