Existing files with "ä" in the filename are silently overwritten when a new file with the same name is uploaded

Steps to reproduce

1. Have a PDF file with the name "ä.pdf" (sic) in your Nextcloud.
2. Have a different PDF file with the same name on your IOS device (Files app).
3. Choose to share the file from your IOS device to Nextcloud.
4. Select the folder where "ä.pdf" already exists.
5. Upload.

Expected behaviour

Get a dialog to choose how to deal with the filename conflict.

Actual behaviour

No dialog. The the existing file is silently overwritten by the newly shared file.

Logs

Nothing in server logs, but here's the app log (at the default level).

Reasoning or why should it be changed/implemented?

The issue leads to data loss. I discovered this when I realized that saving bills from my banking app by sharing them to my Nextcloud had been doing this for who knows how long. (My electricity bills have the service provider name, "Oulun Energia Sähköverkko Oy" in their filename.)

Environment data

iOS version: 17.0.3

Nextcloud iOS app version: "Nextcloud Liquid for iOS 4.9.1.0"

Server operating system:

Web server: Apache 2.4.41

Database: MySQL/MariaDB 10.3.38

PHP version: 8.2

Nextcloud version: 27.1.3.2

Miscellaneous

• This is not reproducible on Android (with my server), which is why I'm pretty sure the fault lies with the IOS app.
• Also not reproducible on IOS with filenames with ASCII-only names (FWICT); this general case was apparently fixed when first reported as #1737.