Our Mosaic Worldpay partners have pivoted to automated learning tools to help make risk reviews more streamlined. Sometimes, when a large individual transaction is submitted (especially when first starting to process), the Worldpay risk team will flag the transaction for additional review and may request information to clear the review and lessen the chance of future reviews, which you can submit to the Mosaic team, as outlined here.
For Stripe Partnerships: There are rare instances where a larger transaction can pose a heightened risk exposure, and should be reviewed for fraud, delivery window risk, and overall chargeback risk. This review serves as a last line of defense to intervene on possible high risk transfers that are on their way to the merchant that could result in a major loss. The goal of these reviews is to identify large transfers and take action to mitigate malicious merchant behavior, loss, and Stripe’s chargeback rate. This could occur if a transaction triggered our internal fraud models based on their transaction history in Stripe ecosystem or other factors that caused us to deem this payment as risky. If a transaction was flagged, you would typically receive an error message or decline when attempting to process a payment. This error should provide you with more details on why this issue occurred but you can always contact support if the error does not provide sufficient details.