Spaces and pins completely wiped if Zen is open on an existing system while setting up sync on a new system (1.22.2b)

Preliminary Checks

• I have read and understood the important section above.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

https://github.com/zen-browser/desktop/issues/14680 seems related, but fairly vague and not attributed the cross-device sync meta.

After the official release of macOS 27 I decided I would completely restore my MacBook to have a "clean install". I had Zen opened on my Mac Studio, so I could access my password manager as I setup my MacBook. As soon as I signed into Zen on the MacBook 100% of the folders and tabs disappeared in Zen on my Mac Studio, and it prompted me to keep/delete every space as they had "been removed on another device".

I believe this is similar to other sync issues I reported during sync's beta phase on Twilight. IE it appears to be some sort of race condition. When I first logged into my Firefox account on my MacBook it seemingly synced it's "blank" configuration to the account, and quickly propagated that blank config to Zen running on my Mac Studio. As far as I can tell there's no method of reversing this outside of deleting the profile data on the opposing computer, closing Zen on all other computers, and completely setting that computer up again.

Expected behavior

When initially setting up Zen sync on a new computer it shouldn't drop all pinned tabs, folders, and workspaces on existing systems who are logged into the same Firefox account with Zen open.

Actual behavior

When initially setting up Zen sync on a new computer all pinned tabs, folders, and spaces are dropped on other systems logged into the same Firefox account with Zen open.

Steps to reproduce

1. Open Zen on an existing system with sync enabled.
2. Login into a fresh install of Zen on a new system.
3. Watch as all pinned tabs, folders, and spaces are dropped on the other system.

Screenshots and videos

Below is Zen that was opened on my Mac Studio as I was setting up sync on my MacBook after a full system restore. You can see that all pinned tabs and folders have been dropped in every space. You'll also notice that one of my spaces is missing, that's because I quickly agreed to the "space has been deleted on another system" prompts, thinking that it was referring to the new space that was created when you first setup Zen on a new system; which I had deleted. Tangential, but it would be nice to drop the the "default space" if it hasn't been changed when you first setup sync on a new system.

Below is zen on the MacBook after initial login/sync, you can see that my space is correctly "preserved" on the new system.

Version

1.22.2b

What platform are you seeing the problem on?

macOS - aarch64

What component is this issue related to?

Sync

Relevant log output if applicable

There were no error logs in the `weave` folder.