Login V2 does not persist selected UI language as user preferredLanguage during self-registration #12657

Preflight Checklist

• I could not find a solution in the documentation, the existing issues or discussions
• I have joined the ZITADEL chat

Environment

ZITADEL Cloud

Version

4.17

Database

No response

Database Version

No response

Describe the problem caused by this bug

During self-registration via the hosted ZITADEL Login V2, the selected UI language is correctly applied to the login interface but is not stored as the user's preferredLanguage attribute. The addHumanUser function in the Login V2 implementation does not pass the preferredLanguage parameter.

To reproduce

1. Access the hosted ZITADEL Login V2 interface
2. Select a non-default language from the language switcher during self-registration
3. Complete the self-registration process
4. Verify the created user's preferredLanguage attribute
5. Observe that preferredLanguage is not set to the selected UI language

Screenshots

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Expected behavior

The selected UI language during self-registration should be persisted as the user's preferredLanguage attribute so that future communications and UI interactions default to the user's chosen language.

Operating System

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Relevant Configuration

No response

Additional Context

This is a feature request to add configuration or automatic behavior to persist the Login V2 locale selection as preferredLanguage during user registration. The user has confirmed this functionality is not currently available in the hosted Login V2.