AI API Price War Heats Up: DeepSeek V4-Pro Cuts 75% & Gemini 3.5 Flash Lands May 31, 2026 is shaping up to be a landmark day in the AI API market. Two developments are converging: DeepSeek V4-Pro's 75% price cut goes permanent — the temporary promo ends, and the discount becomes the new baseline. Google's Gemini 3.5 Flash arrived at I/O 2026, boasting 4x speed and sub-$10 output pricing. The message is clear: the AI API price war is no longer simmering — it's boiling over. The State of Play: Dee