When we get the gravy paypal rows the txn_id they have for Paypal is not the one stored when the donor initiates the payment - causing it not to ingress to CiviCRM @Cstone thinks this may be is a bug at Gravy's end but we can handle in in our Audit / Reconciliation code with a bit of duct tape.
contribution_extra.gateway gravy
gateway_txn_id 08486c38-54e0-4afa-acc2-8b1218234ef9
"backend_txn_id":"43P37729ES2101736" - this one from the reconciliation file
contribution tracking ID 243715804
*original paypal txn ID * "4XY584180P080392D
Contact ID https://civicrm.wikimedia.org/civicrm/contact/view?reset=1&cid=69566112