Google Gemini 3.5 Pro Begins Rolling Out After Missing Both May and June GA Targets

The Agent Report·high signal

Gemini 3.5 Pro, unveiled at Google I/O on May 19, 2026, has finally begun a gradual rollout in early July after slipping past both its June 30 GA date and its I/O commitment, spending weeks in limited Vertex AI enterprise preview. Reporting attributes the delay to three linked issues flagged by early testers: token-efficiency concerns, coding performance below flagship standard, and long-horizon multi-step reasoning that fell short of the I/O demo bar. The slip coincided with four senior DeepMind departures in one week — Noam Shazeer to OpenAI, Nobel laureate John Jumper plus Jonas Adler and Alexander Pritzel to Anthropic — and roughly $225B off Alphabet's market cap.