API Key returns 401 error only from external site, despite all configurations being correct.

[arifnurhakim]

Hello,

I am facing a persistent issue with an API key for my project.

**Project ID:** proyek-veo-final
**API Used:** Generative Language API (generativelanguage.googleapis.com)
**Problem:** All API calls from my web application (hosted on Netlify) consistently fail with a "401 No auth credentials found" error.
However, if I run the exact same code and API key inside a gemini.google.com canvas, it works perfectly. This suggests a backend issue with how my key is validated from external domains.

I have already confirmed the following configurations are correct:

• The project is linked to an active and valid Billing Account.
• My user role is "Billing Account Administrator".
• The "Vertex AI API" is Enabled for the project.
• The API Key has no "Application restrictions" (it is set to "None").
• This issue has persisted for more than 12 hours, so it does not seem to be a temporary sync delay

I am unable to create a support case through the Google Cloud Console because my support plan does not allow for technical cases, and the "Cloud Billing" category is not available to select.

Could anyone from the community or the Google Cloud team provide insight into what might be causing this backend validation issue?

Thank you.