GLM-5.3-Flash will not reach a score of 1480 on the Arena.AI Text Arena overall leaderboard by December 31, 2026. Z.ai named Ox Alpha GLM-5.3-Flash on August 26, 2026, but the Flash SKU is a distinct 320B-A18B product separate from the 743B-base GLM-5.3. Z.ai said open weights were expected roughly…