Google AI Studio deployment on custom domain fails with API key expired error

I deployed a Google AI Studio App under a custom domain:

Pulser | AI Market Sentiment Intelligence

Daily scanning of market news for stocks, crypto, and indices sentiment trends.

Environment

Environment variables GOOGLE_API_KEY and GEMINI_API_KEY have been set.

Error

However, I am getting errors in the Developer Tools:

{
  "error": {
    "code": 400,
    "message": "API key expired. Please renew the API key.",
    "status": "INVALID_ARGUMENT",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.ErrorInfo",
        "reason": "API_KEY_INVALID",
        "domain": "googleapis.com",
        "metadata": {
          "service": "generativelanguage.googleapis.com"
        }
      },
      {
        "@type": "type.googleapis.com/google.rpc.LocalizedMessage",
        "locale": "en-US",
        "message": "API key expired. Please renew the API key."
      }
    ]
  }
}

Stack Trace:

at Dh (index-pSh-MI7v.js:129:4200)
at async index-pSh-MI7v.js:125:5697
at async iC.generateContent