Post #399387 45 Sep 21, 2026, 17:05 UTC Fable 5 – Median thinking declined in Augusthttps://twitter.com/Lon/status/2101793422487204027 X (formerly Twitter) Lon Lundgren (@Lon) on X After Anthropic made Fable 5 permanently available in subscription plans, I noticed a large drop in performance. The model felt dumber, and I couldn't explain why. Measured five different ways, A…