Scroll position of main timeline is reset when opening thread

[MadLittleMods]

Steps to reproduce

1. Jump back in the room history catching up on messages
2. Open a thread you stumble upon while catching up
3. Main timeline scroll position is jumped to the bottom (showing latest messages) ❌

Outcome

What did you expect?

The main timeline should maintain whatever scroll I was at before opening the thread

What happened instead?

The main timeline scroll position is jumped to the bottom (showing latest messages) ❌

Operating system

Windows 10

Browser information

Chrome Version 109.0.5414.120

URL for webapp

https://develop.element.io/

Application version

Element version: 50f2b53-react-4c1e4f5127bd-js-4f918f684e9d Olm version: 3.2.12

Homeserver

matrix.org

Will you send logs?

Yes, https://github.com/matrix-org/element-web-rageshakes/issues/19796

[SimonBrandner]

I can't repro, sadly

[MadLittleMods]

We should really have debug logs that include enough information to be able to figure out whenever and why this kind of thing happens. We should log when a thread is opened and closed because at the very least it's a good point of reference to read from in the logs. Whenever we update the scroll position or reset a timeline, there should be a paper trail to know what triggered it. What made the unread marker appear and disappear, etc (Room was marked unread because event $xxx is in front of unread marker m.read $xxx). Update: Related to #24388

These timeline problems are very annoying and reports are fruitless because these things aren't consistently reproducible and there is no information in the logs to help reproduce later with.