The membership count reported in Recents doesn't match that in Public Rooms - and can also be out of sync with the size of the membership list and the actual observed current members of a room:

[11:13] [08:35:06] Hi guys ...
[11:13] [08:36:12] Speaking of playing with the api, I'm just now playing with it. I have to newly created rooms, and when querying /publicRooms I get (among others) num_joined_members: 49
[11:13] [08:36:27] Where do these other 48 members come from?
[11:13] [09:24:20] weird
[11:13] [09:24:27] sounds like a bug
[11:13] [09:24:54] perhaps you keep rejoining it as the same user and the count keeps increasing?
[11:13] [09:26:44] seems likely: most of the default clients won't rejoin if it remembers it had already joined, but if you're playing with the API then it is possible that this is a failure case we aren't seeing
[11:13] * M-kegan [09:27:08] still doesn't quite get the rationale behind not treating multiple joins as noops
[11:13] [09:27:29] it's a bug surely?
[11:13] [09:28:09] haven't we already established that the public rooms number of users is way off?
[11:13] [09:32:24] iirc federation needs multiple joins for something. It may be a bug that those are being sent to the client maybe, but I don't know.
[11:13] [09:32:32] and yes, it is way off Tor
[11:13] [09:35:02] Looks like a bug to me, I queried directly after creating the room.
[11:13] [09:47:52] that's even stranger then.

[11:29] hm, my script and angular is now off by one for nicks in this channel :p
[11:29] Counting yourself?
[11:29] better than before, wonder who it is that can't count
[11:29] I am in my script, yes

[12:07] Erik: any inspiration on the room count nightmare?
[12:08] *room member count
[12:28] Not really
[12:28] could be the current_state_events table getting out of sync with the actual state
[12:29] or a table is returning duplicate rows somewhere

etc.

(Imported from https://matrix.org/jira/browse/SYN-307)

(Reported by @ara4n)