503 - [Paid Tier 1] gemini-3-pro-image-preview returning prolonged 503 UNAVAILABLE at low request rate

Hello, we’re on paid Tier 1 and seeing prolonged 503s on gemini-3-pro-image-preview.

Time window:

  • Started: Feb 18, 2026 (UTC)
  • Still occurring: Feb 20, 2026 (UTC)

Request pattern:

  • Gemini API (AI Studio key)
  • Low traffic, serial only (concurrency=1)
  • Exponential backoff retries enabled (up to long waits)
  • Still many failures with: 503 UNAVAILABLE / “model is currently experiencing high demand”

Observed behavior:

  • Not a quota error (no dominant 429 pattern)
  • Billing is active and paid tier is confirmed
  • Occasional success can happen, but failure rate remains very high over long periods

Example error:
{'error': {'code': 503, 'message': 'This model is currently experiencing high demand. Spikes in demand are usually temporary. Please try again later.', 'status': 'UNAVAILABLE'}}

Seeing success with a new api key.