How do I set up Flask Postgres containers on Kubernetes cluster?

So I have deployed both the containers and connected my flask to Postgres. For the most part, it works but because there are two Linode servers, when the database query goes to the first, it will work, but if it goes to the second server, it will not find the data in that server. I am sure it is a configuration issue, but I want to understand how I should connect the flask app so that it will have data in all databases, or should I have only one replica of the database and use that server only.

Thank you.