Sliding Sync causes nested spaces improperly populate

[Wolf-Seisenbacher]

Describe the bug

When Sliding Sync is on (Starting in 1.20.0) all nested spaces show up on the left hand bar and not under the spaces they are supposed to be.

Sliding Sync Off

Sliding Sync On

Other issues include ghost unread notifications, as seen in images. These are new issues as of 1.20.0

Reproduction

1. Turn on Sliding Sync
2. ...
3. PROFIT

Expected behavior

Spaces should be nested properly, and read DMs should not be marked as unread.

Platform and versions

Tested on:
Windows 10 IoT LTSC
Gentoo Linux
Android 13

Homeserver:
Synapse 1.150.0 on TrueNAS Core /w BSD 13.5 jail
MAS 1.17.0 on Gentoo Linux

Sable clients tested:
Tauri based Desktop build (Nightly)
Electron Wrapper Desktop Build
Web Client on Falkon + Librewolf + Chromium

Additional context

Latest Nightly build also currently logs me out after a period, requiring logging back in and reverifying the session