Localization not respecting user settings

[scheibling]

Describe the bug
Filing a new bug report for the same issue as #9433 since that one was closed/stale, it seems the locale settings in the web interface are very inconsistently applied.

When I change my language to for example German, it will translate the user settings page to german just after applying the changes. But when I reload the page, log in/out, clear cookies and site data the language will always revert to English

In addition to this, email language also seems to be inconsistently applied even though a specific language is set for a user.

To Reproduce
Steps to reproduce the behavior:

1. Go to user settings
2. Change your language
3. Save changes. You'll se the new language
4. Reload the page, or navigate to a different page
5. Language will revert back to English

Expected behavior
The interface should remain in the chosen language, alternatively it should be configurable if the browser localization overrides that which is set in user settings

Screenshots
n/a

Logs
n/a

Version and Deployment (please complete the following information):

• authentik version: 2024.12.1
• Deployment: helm

Additional context
Fresh install, tested on multiple browsers (ff, edge, safari)