Buying a large amount of foreign exchange in a certain currency far exceeds the amount of RMB exchanged in this currency. If the relationship between supply and demand is unbalanced, foreign goods will appreciate and RMB will depreciate.

For example, recently, the US dollar, due to the interest rate hike by the Federal Reserve, caused the exchange rate difference with the RMB, so the number of dollars purchased increased greatly, resulting in the depreciation of the RMB against the US dollar.