daily_quota_exceeded
HTTP 429, rate_limit_error.
The daily allowance is spent. With a key it belongs to the organization, not the key.
What to do
Wait for the time in Retry-After. Slowing down does not help, and neither does a new key. Without a key, a free one raises the allowance; with one, upgrade_url leads to the plans. A 304 never costs a request.