I think porting to k8s can succeed or fail, like any other project. I switched an app that I alone worked on, from Elastic Beanstalk (with Bash), to Kubernetes (with Babashka/Clojure). It didn't seem bad. I think k8s is basically a well-designed solution. I think of it as a declarative language which is sent to interpreters in k8s's control plane.

Obviously, some parts of took a while to figure out. For example, I needed to figure out an AWS security group problem with Ingress objects, that I recall wasn't well-documented. So I think parts of that declarative language can suck, if the declarative parts aren't well factored-out from the imperative parts. Or if the log messages don't help you diagnose errors, or if there isn't some kind of (dynamic?) linter that helps you notice problems quickly

In your team's case, more information seems needed to help us evaluate the problems. Why was it easier before to make testing environments, and harder now?