Forum Discussion
There are a lot of of articles about tracing the traffic in nginx:
https://www.nginx.com/blog/application-tracing-nginx-plus/
https://www.nginx.com/blog/opentracing-nginx-plus/
https://docs.nginx.com/nginx-ingress-controller/troubleshooting/troubleshoot-ingress-controller/
Also you can check the release notes for known issues and fixes and better run the latest nginx version:
https://docs.nginx.com/nginx-ingress-controller/releases/#nginx-ingress-controller-222
Probably a silly question, but have you checked the logs of the ingress pods?
Also, have you checked any performance graphs in Prometheus to check for ie. CPU throttling?If you managed to get the needed answers, please flag the question as answered.