Major SEO updates on October 13th include the expansion of AI Mode to 35 new languages and 40 countries, the integration of apps like Spotify and Canva in ChatGPT, and Google's release of the Gemini 2.5 model which can interact with websites. Other updates highlight the impact of spam updates on site traffic and Google's efforts to combat review extortion scams. Staying informed on these developments is crucial for SEO professionals adapting to the evolving landscape.