diff --git a/CRM/Core/Payment/PayPalImpl.php b/CRM/Core/Payment/PayPalImpl.php
index 16526443bd0196af4a07b51a7fb726a1d784302d..2820e426c89054ebb3952a349a4bd5a2ae43a49d 100644
--- a/CRM/Core/Payment/PayPalImpl.php
+++ b/CRM/Core/Payment/PayPalImpl.php
@@ -1132,8 +1132,13 @@ class CRM_Core_Payment_PayPalImpl extends CRM_Core_Payment {
     // The contribution form passes a 'button' but the event form might still set one of these fields.
     // @todo more standardisation & get paypal fully out of the form layer.
     $possibleExpressFields = [
+      // @todo - we think these top 2 are likely not required & it's still here
+      // on a precautionary basis.
+      // see https://github.com/civicrm/civicrm-core/pull/18680
       '_qf_Register_upload_express_x',
       '_qf_Payment_upload_express_x',
+      '_qf_Register_upload_express',
+      '_qf_Payment_upload_express',
       '_qf_Main_upload_express',
     ];
     if (array_intersect_key($params, array_fill_keys($possibleExpressFields, 1))) {