Only one bridge of plenty is available for paricipiants

Hi,

im relativly new to jitsi.
First of all you are doing a great job.

We are running actually an environment with jitsi-meet server and lots of bridges.
Its all on ubuntu 18.
Jicofo (1.0-549-1), jitsi-meet (1.0.4025-1) are on the latest versions. Prosody is on 0.10.0
The bridges are jitsi-videobridges2 almost the latest available version.
Bridges (and jicofo) are configered to join a muc.

We faced two problems which might be related somehow and are not desired behavior.

First if users were authenticated as moderators and join another conference they are also moderators and
if the are leaving and come back to this room they are new participiants. The old one of them stay and cannot
be kicked because they are moderators. This leads to confusion.

Are there considerations if somebody was moderator and enters another room that it´s then only paricipiants?
And can be there a main moderator?
If this moderator leaves is there a chance to drop this moderator role to another paricipiant?

Second is and it´s the topic after the last update and some restarts of prosody and jicofo suddenly
the bridges could not join again the muc. There was only a note in jicofo (FINE) log:

Jicofo 2020-04-23 20:02:29.763 FINE: [31] org.jitsi.impl.protocol.xmpp.ChatRoomImpl.log() Ignore a member joined event for jvbbrewery@internal.auth.jitsi.example.org/jvbxyz

What ever i did i could not bring the bridges back to be added by jicofo as available bridges. Even rebooting all of the machines did not change anything.
It seemed only one was left to could be added. But this also changed if i stoped that bridges and played around until another one was taken as available.
So only one could be used. If this was stoped:
Jicofo 2020-04-23 19:26:41.635 SEVERE: [122] org.jitsi.jicofo.JitsiMeetConferenceImpl.log() Can not invite participant – no bridge available.

This brought me to a discussion we led on this day. The limit of max 75 paricipiants in a conference.
So i thought it might be that there are lots of leftovers in the muc of the bridges and maybe they cannot enter because it´s full.
So i changed the name of the muc where jicofo and the bridges are joining and hurra after restarting the bridges every of it were joining
and added by jicofo as available bridges.

This brings me to some questions:

Is there also a limit of 75 bridges in a muc?
Is there a clean up somehow possible through jicofo?
Is this a bug?

And why i thought this is maybe related to paricipiants stuck in the room is if a bridge is restarting (Or goes down on some reason)
and is not leaving correctly the room, it stays. If it´s then comes back as a new paricipiant the muc fills up and after sometime
no bridge can join the room again because it´s “full”. And even after restarting jicofo (and prosody and everything else of course).

Regards, Kai