Inactive user was idle-kicked on the IRC side but not Matrix side, despite sufficient privileges

[progval]

This differs from #1564 because it is about Matrix users that are privileged and from #1575 because it is about unprivileged appservice. (so in both cases, the appservice doesn't have permission to kick)

Here, this is about a non-admin user in #irc:matrix.org, where the appservice is correctly configured. Yesterday, this Matrix puppet was kicked as part of the bi-daily reaping:

09:00:04 <-- Vivia[m] (~viviagnom@2001:470:69fc:105::1:cb33) has quit (Quit: You have been kicked for being idle)

but no corresponding kick was issued on the Matrix side.

Then, the next time someone on IRC posted a message, it was dropped by the privacy filter as usual and the puppet immediately reconnected, as usual:

22:43:30 <Salt> Hi, is something going on with the librera.chat bridge? I am unable to join a couple of room s(that I thought I was in) just spins and times out. #indieweb:libera.chat is one of them
23:56:52 <ieure> Seems broken, I haven't seen anything from users on the Matrix side at all today.
23:57:09 --> Vivia[m] (@vivia:gnome.org) (~viviagnom@2001:470:69fc:105::1:cb33) has joined #matrix-irc
06:45:30 <val> Salt: hard to say, it's often like this
06:46:04 <val> ieure: now *that* is a new problem: https://github.com/matrix-org/synapse/issues/15216

(Salt is from Matrix, ieure and val are from IRC; timestamps are UTC)

And on the Matrix side (seen from matrix.org):

("Hier" means "yesterday", "Aujourd'hui" means "today", and you can see the usual org.matrix.appservice-irc.connection event of the privacy filter; and despite the lack of pill, ieure is correctly synced to the Matrix member list)