Jenkins kubernetes-plugin not understanding env variable in scripted pipeline

Jenkins version 2.235.2

kubernetes-plugin version 1.26.4

I'm trying to parametrize the yamlFile used as pod template with a env variable based on the branch I'm building. What I have right now is:

pipeline {
  environment {
    MASTER_BRANCH = "origin/dev"
    BUILD_POD = "${env.GIT_BRANCH == env.MASTER_BRANCH ? 'jenkins/build-pod-prod.yaml' : 'jenkins/build-pod.yaml' }"
  }
  agent {
    kubernetes {
      idleMinutes 3
      yamlFile env.BUILD_POD
      defaultContainer 'docker'
    }
  }
}

But that is taking a default template with just the jnlp container. I've tried also putting:

yamlFile env.BUILD_POD
yamlFile "${env.BUILD_POD}"
yamlFile "${BUILD_POD}"
yamlFile "$BUILD_POD"
yamlFile $BUILD_POD

But none of that worked. I don't know if it's some misunderstanding from my side or a bug.

I tried also to do the pipeline as a scripted one, which seems like more versatile, but I cannot now neither how to accomplish what I need.

Thanks all in advance.