@anton.barkovsky
Thank you so much for quick response. I am not pretty sure, but below are the findings so far.

The same docker container is used by 30+ applications. All applications are working fine until last week and all of a sudden all apps are going down one by one. Our preliminary analysis is all projects using flask are going down where as apps not using flask are good.
We use Kubernetes service layer, so we are checking if there is anything suspicious upgrade happened there as well.
I am trying to explore more to see if anybody faced such issues with flask
Eg: https://stackoverflow.com/questions/24884901/python-flask-webserver-stop-responding

Thanks much for taking time