1, foreign exchange control is not only to prevent the devaluation of the local currency, but to balance the balance of payments and maintain the exchange rate of the local currency. We should not only prevent devaluation, but also prevent excessive appreciation.

2. The understanding that insufficient foreign currency supply leads to appreciation is also wrong. This is not a commodity (although many currencies are called commodity currencies). Foreign exchange control is more often to prevent the outflow and excessive inflow of assets from affecting economic stability (with foreign exchange reserves), while the depreciation and appreciation of the local currency are more often affected by domestic economic data, economic policies and interest.

PS, things are scarce at any time. The so-called pushing up the exchange rate is mostly a carry trade, which is a speculative arbitrage transaction under the influence of interest rates. In other cases, exchange rate changes depend on the domestic economy.