Forgot Dispose in TwistChainStep1 and TwistChainStep2.

Assets/AnimationRiggingWorkshop/Constraints/TwistChainStep1.cs

 
         public override void Destroy(TwistChainStep1Job job)
         {
+            job.chain.Dispose();
+            job.steps.Dispose();
         }
 
         public override void Update(TwistChainStep1Job job, ref TwistChainStep1Data data)

Assets/AnimationRiggingWorkshop/Constraints/TwistChainStep2.cs

         public override void Destroy(TwistChainStep2Job job)
         {
             job.chain.Dispose();
+            job.steps.Dispose();
         }
 
         public override void Update(TwistChainStep2Job job, ref TwistChainStep2Data data)