[10.11.6] Renaming a user account to contain the symbol `&` causes jellyfin UI to just show the spinning thinking animation

[loongemperor]

Description of the bug

Trying to rename a user account in jellyfin to a name that contains & causes it to keep on showing the spinning thinking animation until you give up and close it or navigate away.
unlike renaming to a valid user name without said symbol which successfully finishes in a fraction of a second.

Reproduction steps

1. sign in on the jellyfin web client, with an admin account, using a browser of your choice.
2. navigate to the dashboard.
3. select Users
4. click on any user
5. change the Name field from A to A&B
6. click "save" at bottom of screen.

What is the current bug behavior?

When clicking save, it just starts showing the spinning thinking animation forever.

What is the expected correct behavior?

Either:
A. tell the user that the symbol & is forbidden and they should use a different symbol
B. change the name if it is not a forbidden symbol.

Jellyfin Server version

10.11.6

Specify commit id

No response

Specify unstable release number

No response

Specify version number

No response

Specify the build version

10.11.6

Environment

- OS: 25.10.1 - Goldeye
- Linux Kernel: LTS 6.12.33
- Virtualization: Docker
- Clients: Browser
- Browser: Brave
- FFmpeg Version: not applicable
- Playback Method: not applicable
- Hardware Acceleration: none
- CPU Model: AMD Ryzen 5600G
- GPU Model: iGPU
- Plugins: none
- Reverse Proxy: none
- Base URL: ?
- Networking: not applicable
- Jellyfin Data Storage & Filesystem: ZFS ixVolume (dataset auto generated and managed by truenas)
- Media Storage & Filesystem: ZFS mounted hostpath dataset
- External Integrations: none.

Jellyfin logs

not a single line was generated in logs for this event.

FFmpeg logs

Client / Browser logs

No response

Relevant screenshots or videos

No response

Additional information

No response