Unexpected data loss for extensions, local storage, etc. in Edge Beta

[yfdyh000]

I haven't found a similar report, and this is very unusual for me.

A few days ago, after I opened Edge, I noticed that all extension icons became default (blank), but others looked fine. Soon more things became default (like asking for default browser), but history, bookmarks and tabs were kept. Eventually I noticed that all installed extensions' files were lost (the list was kept, but all "corrupted"), and the extension's data was also gone, including data that wasn't backed up. I noticed that folders like "User Data.CHROME_DELETE" appeared, which contained a lot of files, but it didn't seem to contain extension files and data. I have never switched Edge versions to other branches.
Today, Edge doesn't start (hangs, seem more than 1 hour) for me, had to kill the process and restart, then I noticed that this was happening again. Many extensions are kept at this time, but some are "corrupted" again. It appears that all extensions data is lost again, the history is a few days ago, and was synced to retrieve some. Cookies is lost.
At this time, in AppData\Local\Microsoft\Edge\User Data\Snapshots, I see "103.0.1264.71" (07-28) & "103.0.1264.77" (07-31) folders, contains backups of some important files. But I don't think this includes the extensions storage that I value most (including things like OneTab).

Maybe something related for config:
* In my config, the AppData\Local\Microsoft\Edge Beta\User Data is a symlink to AppData\Local\Microsoft\Edge\User Data, I don't remember the exact reason, but it was at peace in the previous few dozens of months.
* C drive is occasionally less well-off, but I don't think this should cause data loss.
* A few days ago, I moved out the Group Policy - Computers - CacheDir, and added the Group Policy - Current User - CacheDir (i.e. https://docs.microsoft.com/DeployEdge/microsoft-edge-policies#diskcachedir). It points to the same directory on another HDD.

* Launch Enhanced Options and Windows Update, maybe related, possibly it starts Edge stable and causes some data migrations, and a big failure for backups.

104.0.1293.35 in Edge Beta's edge://version for now.

[#2]

Sharing app data between different Edge channels is an unsupported scenario because new versions of the browser can introduce breaking changes to data formats at any time, and if older versions of the browser encounter that data, they won't know how to handle it and the behavior will be undefined.

[#3]

This sounds fair, but the backup process of the version downgrade appears to have resulted in unexpectedly data losses, these backup is incomplete and lost is unknowingly. My specific extension's local storage data used to be reset occasionally, I'm not sure if that's related, just.

I expected it to give a warning to refuse to start. I hope this behaves well if users have to downgrade their own user data to an earlier version (instead of a channel), like allowing imports to migrate user data. Sync is good guy, but it has some limitations like size limit and looks unstable / uncontrollable, I miss some history and tabs have changed recently.

[#4]

I believe those backups only capture certain data by design; they're mainly there for businesses who use our defined rollback process, so they only are taken near version change boundaries and thus will be out of date for day to day usage.