while invoking REST API in gen3 throwing oracle.cloud.connector.api.CloudInvocationException

The REST API was working as expected in OIC Gen2 even via postman it is also working but when I try to achieve the same in OIC Gen3 then it is causing issue and throwing the below error

oracle.cloud.connector.api.CloudInvocationException

CloudInvocationException [ Fault Details :
<ns0:APIInvocationError xmlns:ns0="http://xmlns.oracle.com/cloud/generic/rest/fault/REST/process">ns0:title/ns0:errorCode/ns0:typehttp://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.5.3</ns0:type>Bad Gateway</ns0:title>ns0:errorCode502</ns0:errorCode><![CDATA[InboundJaxrsResponse{context=ClientResponse{method=POST, uri=https://apis-uat.lab.technipenergies.com/techno/salesforce/upsert, status=502, reason=Bad Gateway}}]]></ns0:errorPath>ns0:instance<![CDATA[{"error":{"code":"NoResponse","message":"The server did not receive a response from an upstream server. Request tracking id '08584742808334060834317880368CU00'."}}.The HyperText Transfer Protocol (HTTP) 502 Bad Gateway server error response code indicates that the server, while acting as a gateway or proxy, received an invalid response from the upstream server. There could be several reasons including 1) The domain name not resolvable, 2) The origin server is down, 3) A firewall or another intermediary blocks the request. Try to replicate the same request using the same set of intermediaries using cURL or any other REST client. You can trace