There may be many reasons why Jiang Zhiyi, the old uncle of Qiantang, no longer participates in mediation. First of all, he may be old, and his physical condition may not be suitable for long-term high-intensity mediation work. Secondly, the epidemic may have affected his life and work, and he may choose not to participate in mediation for health or other reasons.

This is just speculation, and the specific reason may need to ask him or learn more relevant information and background.