Steps to reproduce: - Set `muc_tombstone_expiry` to a low value for easier testing e.g. 120 seconds - Reload the config and mod_muc - Run `muc:list("conference.example.org")` to note the number of rooms on the muc component - Destroy a room - Wait for the tombstone_expiry period to finish e.g. 120 seconds - Run `muc:list("conference.example.org")` again. The number of rooms will be unchanged, and the destroyed room is still listed. In fact, the destroyed room can also be seen in `Service Discovery` using a client like Gajim. For instance, I have rooms that I destroyed months ago, that still show up in the shell and in Service Discovery, and their reported number of participants is zero. Note: there is no cron task that deletes rooms with expired tombstones. The only cron task that I have on conference.example.org is "Remove expired messages" This issue was observed in prosody 0.12 and prosody 13.0