Istio+Grafana 101: why do services not in the mesh appear on Mesh Dashboard?

My configuration:

  • istio 1.8.5, installed via helm and enabled on a small subset of namespaces, labeled with
    → Can’t use a newer version as our k8s clusters are still 1.16.x
  • prometheus addon instance installed just for istio scraping
  • Company-wide grafana 6.6.0, using the dashboards present on

My doubt is regarding what I think may be “too much data” appearing on the Istio Mesh Dashboard. On the HTTP/gRPC Workloads table, grafana shows many workloads that aren’t “istio enabled” and end up showing up with NaN data. I even got a few “-” services.

Is this expected? Shouldn’t istio return only the services/workloads where it’s enabled?

Is there a way to restrict the scraping to the istio-enabled namespaces?