The VM availability metric is calculated as an aggregation of the health checks stated here. When the guest agent is incorrectly installed or missing altogether, we interpret the guest heartbeat signal as unhealthy, and therefore emit a metric value of 0, which may be inaccurate. We have plans to move away from the aggregation model and rely only on one, unified high confidence signal from the host server. This work is already underway and will ensure our monitoring offerings give consistent values. We anticipate this work to be completed through the course of 2023.