TUS upload of new files with backslashes in filename fails with 412 Precondition Failed, but rename to backslash succeeds

[Xardas220]

Environment:
OpenCloud Server in Docker 4.0.7
OpenCloud Desktop Client 3.0.3.2073
macOS client
TUS upload enabled

Steps to reproduce:

1. Create a local file with a backslash in its filename, e.g.
   DICOM\PA000001\ST000001\SE000007\IM000024
2. Let OpenCloud Desktop Client sync it.
3. Observe TUS POST:
   POST /dav/spaces/$
4. Server returns 412 Precondition Failed.
5. File is added to client blacklist.
6. Rename the file so backslashes become slashes.
7. Client uploads it; server shows colons instead (behavior of MacOS: Slash is shown in Finder but on data level slashes are colons).
8. Rename the already uploaded file back to backslashes.
9. Rename sync succeeds and file is visible in Web UI with backslashes and is syncing correctly.

Expected:
Either new files with backslashes upload successfully via TUS, or the desktop client rejects them before upload with a clear unsupported-character message.

Actual:
Initial TUS upload fails with 412 Precondition Failed, but subsequent rename to the same backslash-containing name succeeds.

Setup:
Server is started via docker compose. It's standard compose file provided online.

If additional details are needed I can give it. Feel free to reach out.