After attempting the upgrade through the Rancher UI, I noticed that the CRDs are upgraded, but the app is at the older version

% helm --kube-context=... -n cattle-monitoring-system list --all
NAME                  	NAMESPACE               	REVISION	UPDATED                                	STATUS  	CHART                                            	APP VERSION
rancher-monitoring    	cattle-monitoring-system	2       	2024-08-23 14:46:51.478744389 +0000 UTC	deployed	rancher-monitoring-103.1.1+up45.31.1             	v0.65.1
rancher-monitoring-crd	cattle-monitoring-system	4       	2025-06-26 00:06:44.869156938 +0000 UTC	deployed	rancher-monitoring-crd-106.1.2+up69.8.2-rancher.7

Yeah, I think the old release created a PSP...

helm --kube-context=r/macc-kdev -n cattle-monitoring-system get manifest rancher-monitoring

in the output...

---
# Source: rancher-monitoring/charts/prometheus-node-exporter/templates/psp.yaml
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: rancher-monitoring-prometheus-node-exporter
  namespace: cattle-monitoring-system
  labels:
    <http://helm.sh/chart|helm.sh/chart>: prometheus-node-exporter-4.20.0
    <http://app.kubernetes.io/managed-by|app.kubernetes.io/managed-by>: Helm
    <http://app.kubernetes.io/component|app.kubernetes.io/component>: metrics
    <http://app.kubernetes.io/part-of|app.kubernetes.io/part-of>: prometheus-node-exporter
    <http://app.kubernetes.io/name|app.kubernetes.io/name>: prometheus-node-exporter
    <http://app.kubernetes.io/instance|app.kubernetes.io/instance>: rancher-monitoring
    <http://app.kubernetes.io/version|app.kubernetes.io/version>: "1.6.0"
    jobLabel: node-exporter
    release: rancher-monitoring
spec:
  ...

I got help in the Kubernetes workspace under #helm-uses. There's a plugin called helm-mapkubeapis fixed up the existing release "manifests"; When I looked at

helm get manifest rancher-monitoring --revision N

, it looks like the PodSecurityPolicy was removed from the history so it was able to continue the upgrade and skip deleting a resource from an API that no longer exists

# add rancher repo
helm repo add rancher <https://charts.rancher.io/>
helm repo update

# add mapkubeapis plugin
helm plugin install <https://github.com/helm/helm-mapkubeapis>

# Upgrade snippets
helm -n cattle-monitoring-system list
helm -n cattle-monitoring-system mapkubeapis rancher-monitoring
helm -n cattle-monitoring-system upgrade rancher-monitoring-crd rancher/rancher-monitoring-crd --reset-then-reuse-values --wait
helm -n cattle-monitoring-system upgrade rancher-monitoring rancher/rancher-monitoring --reset-then-reuse-values --wait