We're using the /v1/alerts/groups API endpoint to query all alerts and show them on dashboard using an internal tool.

This works well, except when Alertmanager is restarted for a deployment. The silenced field exposed by the above endpoint is populated by the dispatcher, which has to iterate through every alert and set the silenced field when AlertManager starts up. If you have thousands of alerts, this can take a while, and in the meantime our dashboard shows lots of alerts we know are silenced.

This bug report is not very detailed yet and happy to provide more info, but I'm raising it early in case there are some plans afoot to change this behaviour.