nginx – Getting 502 when executing /chat/completions endpoint in staging environment

I’ve been scratching my head over this issue for a few days now. We have three environments – dev, stg and prod. In dev and stg (haven’t done prod yet) environments running /chat/completions endpoint produces different results. In dev executing endpoint with stream=true and stream=false produces expected results. In stg however, when running endpoint with stream=false produces expected results, but stream=true returns 502 every time. 502 comes from our proxy nginx service.
The configurations between two environments are the same, except some ingress setup in k8s deployment.

How would I go about figuring out what’s the cause of the error? Is this OpenAI issue or something else? I should note that 502 comes back almost right away.