The withholding is an additional procedure to the processing time, in which the finance department must look into client's account details, transaction information and limits before the funds are credited into the wallet or transferred to bank account.
As soon as we are notified about a transaction request, the withholding time is taken for security reasons. The length of this process may vary considering the number of wire transfers previously requested by a user, amount, currency and date requested as it's only considers business days. Usually, the first wire transfer often consumes the maximum withholding (up to 3 days for USD and 5 days for CAD wire transfer) on top of the processing time whereas the following deposits/withdrawals wire transfers can take less time. This will depend on local financial institution internal procedures/ business days or local regulation, which in some cases, can delay this process.
The processing time; however, is related to the transaction process regarding the moment the wire request is made, senders' bank executing the payment to the other end institution, and informing the receiver (Coinfiled) that there's a payment on hold.
Please check this link for full information: Fees and Processing Time