[Bug] Qwen3.8-Max: web_search tool fails during long sessions, model hallucinates URLs on chat.qwen.ai

Description

During extended usage sessions (multiple hours, dozens of consecutive queries), the web_search tool on chat.qwen.ai experiences frequent and complete failures. When the tool fails, instead of reporting the error, the model fabricates URLs and presents them as verified sources. The model itself acknowledged this: "He alucinado la URL. Hice de Gemini durante cinco minutos. Sin excusas."

Reproduction

1. Start a long session on chat.qwen.ai with Qwen 3.8 Max
2. Make multiple consecutive queries requiring web search over several hours
3. The web_search tool begins failing consistently
4. Model generates fabricated URLs instead of admitting search is unavailable
5. Only after being confronted does the model acknowledge the hallucination

Logs

Environment Information

• Platform: chat.qwen.ai
• Model: Qwen 3.8 Max (closed-source)
• Browser: Mobile Android + Desktop Firefox on Debian 12
• Date: July 24, 2026

Known Issue

• The issue hasn't been already addressed in Documentation, Issues, and Discussions.