Per the comments found here https://github.com/prometheus-community/helm-charts/blob/main/charts/kube-prometheus-stack/values.yaml#L2367, updating your Helm values to include the following block should resolve this issue:

      prometheusOperator:
        admissionWebhooks:
          annotations:
            argocd.argoproj.io/hook: PreSync
            argocd.argoproj.io/hook-delete-policy: HookSucceeded
          mutatingWebhookConfiguration:
            annotations:
              argocd.argoproj.io/hook: PreSync
          validatingWebhookConfiguration:
            annotations:
              argocd.argoproj.io/hook: PreSync
          patch:
            annotations:
              argocd.argoproj.io/hook: PreSync
              argocd.argoproj.io/hook-delete-policy: HookSucceeded