try

convex/world.ts

@@ -192,7 +192,7 @@ export const leaveWorld = mutation({
       throw new Error(`Invalid world ID: ${args.worldId}`);
     }
     // const existingPlayer = world.players.find((p) => p.human === tokenIdentifier);
-    const existingPlayer = world.players.find((p) => p.human === oauthToken);
+    const existingPlayer = world.playersInit.find((p) => p.human === oauthToken);
     if (!existingPlayer) {
       return;
     }