Airwallex’s Shopify plugin takes your Payers to an Airwallex hosted page to process payments and redirects them back to your website post payment success. When redirecting back to your website, Google Analytics starts a new tracking session because the Payer is coming from a source under the Airwallex domain. This can mess up your conversion data and the original source tracking because Google Analytics attributes every sale to the last source before landing on the order confirmation page – which in this case would be Airwallex.
To fix this issue, you can add “airwallex.com” to the “referral exclusion list” in Google Analytics so it will be skipped as the last referral source before landing on the payment confirmation page.