🛠️ Try using a name-based index for the container.

Kustomize docs claim this should work but I'm not sure if a specific version is required.

Author: coderanger

config/manager/kustomization.yaml

@@ -23,4 +23,4 @@ vars:
     version: v1
     name: controller-manager
   fieldref:
-    fieldpath: spec.template.spec.containers[0].image
+    fieldpath: spec.template.spec.containers.[name=manager].image