What does it mean in the temporary increase of the US Mission?

The temporary withdrawal of the US delegation is to give you an available quota in advance, and then give money after using it.

Temporary withdrawal is actually also called temporary quota, and it has a validity period. After the expiration, the line will be "returned to its original shape" and automatically restored to the original credit line, and the temporary line will no longer be used. When using the temporary line, you must evaluate your repayment ability, and don't wait until the bill comes out to find that you are unable to repay at all.