Withholding keys causes new megolm sessions to be created at every interaction

[tonkku107]

Steps to reproduce

1. Enable "Never send encrypted messages to unverified sessions from this session" or the "Exclude insecure devices when sending/receiving messages" labs flag.
2. Get a friend who you haven't verified with or who hasn't verified all of their own devices.
3. Start sending messages in an encrypted room and observe the console and/or view the original source of events

Outcome

What did you expect?

The application to remember which devices were withheld from the session to prevent unnecessary keys from being created and shared.

What happened instead?

New sessions are created for every message and whenever you start typing. In logs you can see lines related to to-device messages for sharing room keys along with m.room_key.withheld. In the event source you can see session_id is different for every message.

Operating system

Arch Linux

Application version

Element version: 1.11.91 Crypto version: Rust SDK 0.8.0 (21f7cc7), Vodozemac 0.8.1 (also confirmed on web with the same version and Chrome Beta 133.0.6943.35)

How did you install the app?

https://archlinux.org/packages/extra/x86_64/element-desktop/ (https://hub.docker.com/r/vectorim/element-web)

Homeserver

Synapse 1.123.0

Will you send logs?

Yes