In #13756 it became apparent that we have several Prometheus recording rules whose only appearance is in the Prometheus console file here: https://github.com/matrix-org/synapse/blob/develop/contrib/prometheus/consoles/synapse.html

I have never used this and have never seen anyone use this.

@richvdh touched it most recently — do you use it?

If nobody uses it (I wonder if it was 'the answer' before Grafana), I suggest we remove it, or at least remove the recording rules that aren't used anywhere else, in order to cut down on how much useless stuff we record in Prometheus.