The issues related to Prometheus Exporter 1.0.4 image need to be release noted in 2.2.0 release notes.
Release note should be:
The Prometheus Exporter which the Dynamic Admission Controller will set up by default has known issues*. We recommend updating couchbaseclusters.spec.monitoring.prometheus.image https://docs.couchbase.com/operator/current/resource/couchbasecluster.html#couchbaseclusters-spec-monitoring-prometheus-image to "couchbase/exporter:1.0.5" for the latest updates.
* this should link to PE release notes, which I know we don't have but should create.