502 bad gateway error on AWS kubernetes cluster with nodejs application

Question

Getting 502 bad gateway error while doing performance testing it occurs randomly on random API only 2-3 times in a 30 min execution

ingress logs show this error 11.150.71.00 - - [22/Dec/2022:10:44:17 +0000] "POST /api/quotes/test HTTP/1.1" 502 150 "-" "AmazonAPIGateway_hodcqxftdw" 1466 0.030 [cpq-cpq-server-service-9001] [] 11.150.71.177:9001 0 0.028 502 1322918b6f840892739d4dcf194e2226

I have added keep alive time for ingress still no success, CPU and Memory both are stable there is no spike

Ingress.yml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: testIngress
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/auth-tls-secret: "test/test-secret"
    nginx.ingress.kubernetes.io/auth-tls-verify-client: "off"
spec:
  rules:
  - host: test.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: testService
            port:
              number: 9001