Futures are usually bought and sold with leveraged funds. When the buying and selling directions are the same, the profit of its account is multiplied by leverage.
When the buying and selling directions are inconsistent, the account will lose money, and the loss will be enlarged with the leverage ratio.
Therefore, the Agricultural Bank of China's gold shorting later suffered a loss of 200. Due to the use of leveraged funds, the funds obtained from sales are amplified by leverage ratio. This is why 400 is deducted. Judging from the profit and loss of the topic, the leverage doubles.