ChatGPT search queries using domain-specific filtering jumped from under 0.5% to 16-17% of all search fanouts following the GPT-5.6 rollout, while simultaneously throttling sources like Reddit. This aggressive shift toward targeted domain-restricted search breaks traditional open-web and forum-seeding discovery strategies for production LLM integrations. To maintain visibility in user-facing LLM searches, teams must pivot their generative engine optimization from broad web-indexing tactics to securing authority within these highly concentrated domain filters.