[Bug]: Zitadel does not honor "Light Mode only" when after user logs in with another browser or in private mode

[wlinna]

Preflight Checklist

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

Environment

Self-hosted

Version

v2.49.2

Database

PostgreSQL

Database Version

No response

Describe the problem caused by this bug

I have set the branding setting to Light Mode only in Firefox with Zitadel Admin.
It works fine for the browser session that was used for configuring the branding.
It also works in login screen.

However, as soon as I log in with another browser or use private mode with the same browser, the configured branding ceases to show.

To reproduce

1. Configure your desktop / browser to use Dark mode.
2. Open Zitadel in Firefox and log in as Zitadel Admin
3. Go to Default settings > Branding
4. Set Light mode only
5. Open Chromium. Observe that the login screen is light (as it should)
6. Log in as Zitadel Admin. Observre that the screen is dark again

Screenshots

Expected behavior

Zitadel should use Light Mode in all views for all users when Light Mode only is set.

Operating System

Pop!_OS 22.04
Firefox 125
Chromium 124

Relevant Configuration

No response

Additional Context

No response

[hifabienne]

I quickly tested this, and I am currently not sure if the ZITADEL Management console even has the lightmode/darkmode only implemented. When I change to lightmode in my settings it does change for the login ui, but not for the console

[wlinna]

For me the whole console changes color to light. But maybe the "only" part of Light Mode only isn't implemented. And it remembers (maybe with cookies / localStorage) that setting.