When Thanos is enabled, monitoring values add istio-certs via a volumeMount to the thanos sidecar. The configuration currently appends volumes: and volumeMounts: but should be just volumeMounts. See https://repo1.dso.mil/big-bang/bigbang/-/blob/master/chart/templates/monitoring/values.yaml?ref_type=heads#L416 This was quietly ignored up until helm4 update which enforces stricter schema validation and results in the error: ``` Helm install failed for release monitoring/monitoring-monitoring with chart monitoring@83.4.0-bb.2: failed to create typed patch object (monitoring/monitoring-monitoring-kube-prometheus; monitoring.coreos.com/v1, Kind=Prometheus): .spec.thanos.volumes: field not declared in schema ``` You can see the valid values for the spec - https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api-reference/api.md#thanosspec