gemini-3.1-pro-preview started failing on April 15, 2026 with 503/504 after ~2 months of stable usage

Hi,

We have been using gemini-3.1-pro-preview in production for about 2 months without this issue.

The problem started on April 15, 2026.

What happens:

  • requests to gemini-3.1-pro-preview suddenly became much slower
  • some requests hang for several minutes and then fail with 504 DEADLINE_EXCEEDED
  • some requests fail with 503 UNAVAILABLE / high demand
  • the issue appears to be specific to gemini-3.1-pro-preview

First clear failures we observed:

  • April 15, 2026 at 13:10 UTC: very long request ending with 504 DEADLINE_EXCEEDED
  • April 15, 2026 at 13:28 UTC: 503 UNAVAILABLE / high demand

Before that, the same workflow had been working normally, and we had not seen this behavior during roughly 2 months of usage.

Did anything change on Google’s side for gemini-3.1-pro-preview around April 15, 2026?
Has anyone else seen the same regression starting that day?