The API Pod in tandem-qxvn9t has not started:

kubectl get pods -n tandem-qxvn9t
kubectl describe pod market-api -n tandem-qxvn9t

Read the Init Containers: section and the init container's logs with -c. It waits for a Service named market-db on port 5432. Create the database Deployment and expose it; do nothing to the API Pod.