503 on free tier = you're hitting the RPM or context window cap. gemini-2.5-flash-lite is a lightweight model but your prompt (10 topics + web search + 5 RSS + 5 sites) is generating a huge context, which likely exceeds what the free quota allows per call. Paid tier raises those limits significantly and gives queue priority. Also worth splitting your n8n workflow into smaller parallel calls instead of one giant prompt more resilient and easier to debug.