I've taken a look at your transfer xxxxxx, and can see that your money was sent out via the SWIFT International payment method.
If you send money in a currency that isn't the standard currency for that recipient's country, (in this case sending funds to arrive as USD outside of the US in Cambodia), then a SWIFT transfer is the only option.
When sending money with SWIFT, it moves from the sending bank through several intermediary banks before reaching your recipient's bank, where the money is deposited.
Whilst our own fee will always be visible when you set up your transfer, these intermediary banks have their own, separate fees, so your recipient may get less than you intended. For this reason we will always show you a warning message regarding the possible extra charges.
Unfortunately, there's no way for TransferWise to estimate what this fee will be, in advance. You can read more about using SWIFT here.