Description of problem:

When a cluster is switched to use the CustomNoUpgrade feature set without any additional .spec.customNoUpgrade configuration, the version-keyed item under .status.featureGates becomes empty (no enabled/disabled gates):

spec:
  featureSet: CustomNoUpgrade
status:
  featureGates:
  - version: 4.19.0-0.nightly-2025-06-03-070127

According to joelspeed this is not the expected behavior (controllers can intentionally panic when when they cannot find whether their gates are enabled or disabled).

Version-Release number of selected component (if applicable):

Initial report by rhn-support-jianl was some 4.19 cluster bot cluster, I reproduced with 4.19.0-0.nightly-2025-06-03-070127

How reproducible:

Managed to reproduce on a first attempt with a cluster bot cluster obtained with launch 4.19 aws,no-spot

Steps to Reproduce:

$ oc patch featuregates.config.openshift.io cluster --type=merge --patch '{"spec":{"featureSet":"CustomNoUpgrade"}}'
$ oc get featuregate cluster -o yaml

Actual results:

No enabled/disabled gates in the .status.featureGates item

apiVersion: config.openshift.io/v1
kind: FeatureGate
metadata:
  annotations:
    include.release.openshift.io/self-managed-high-availability: "true"
  name: cluster
  ...
spec:
  featureSet: CustomNoUpgrade
status:
  featureGates:
  - version: 4.19.0-0.nightly-2025-06-03-070127

Expected results:

apiVersion: config.openshift.io/v1
kind: FeatureGate
metadata:
  annotations:
    include.release.openshift.io/self-managed-high-availability: "true"
  name: cluster
  ...
spec:
  featureSet: CustomNoUpgrade
status:
  featureGates:
  - disabled:
    - name: AWSClusterHostedDNS
    - name: AdditionalRoutingCapabilities
    ...
    enabled:
    - name: AWSEFSDriverVolumeMetrics
    - name: AdminNetworkPolicy
    - name: AlibabaPlatform
    ...
    version: 4.19.0-0.nightly-2025-06-03-070127

Per Joel the behavior for CustomNoUpgrade without further configuration should match the one for the Default feature set

Additional info

Attaching a config-operator log from a cluster that was installed with a default feature set and around 14:37:21.707399 it was made CustomNoUpgrade with an oc patch command from How to Reproduce section.