Call member count decreases automatically after some time

[bblacher]

Steps to reproduce

1. Start a new element call / join an existing one from element web/desktop
2. Stay in the call for a long time (3+ hours)
3. Watch the call member count go down after some time

Outcome

What did you expect?

The call member count should only go down after someone leaves the call

What happened instead?

The call member count decreased while noone left the call

Operating system

Arch Linux / Windows 11

Browser information

Element Desktop v1.11.92

URL for webapp

call.element.io / call.element.dev

Will you send logs?

No

[bblacher]

Something to add here:
When changing to call.element.dev, the members that don't contribute to the call count don't show tiles.
While reading #2972, I noticed that this might be the same issue, if that's the case, please close this one. :)

[bblacher]

Update: This happens exactly 4 hours after joining.

• Alice joins at 9:16 --> Members: 1
• Bob joins at 9:32 --> Members: 2
• Alice has been a member of the call for 4 hours at 13:16 --> Members: 1
• Bob has been a member of the call for 4 hours at 13:32 --> Members: 0

MSC4140 isn't enabled on my server, enabling it doesn't change this behavior.

[robintown]

4 hours is exactly the duration we set for the expires field of the call membership state events. So I suppose we have a regression here where the membership manager is just not refreshing the state events.

[robintown]

@toger5 is on that issue with the implementation of the new MatrixRTC membership manager in matrix-js-sdk which is being tracked by #2972