NEW · Severity High. On November 12, Google announced Gemini 4 Hydrogen's global deployment in Google Search, improving AI Mode's handling of multi-part questions, parallel query fan-out and visual structured answers. Google says it expands relevant website linking and brings more images, comparison tables and custom tools to AI responses; these are company claims, not independently measured traffic effects. What changed: a major AI Search model upgrade available globally to Search users, with Hydrogen also powering challenging AI Overviews. Who it affects: publishers, SEO teams, ecommerce sites and businesses dependent on Google Search referrals. Action: monitor Search Console and AI Search referral patterns, especially for complex queries and visual comparison content, without assuming a ranking penalty. Deadline: none announced.