Bug AddForce cause inconsistent jumping

I have a little game project going on, im trying to copy Icy Tower. But there is a little problem with that. In icy tower when the player reaches max amount of velocity at x axis player jumps higher than normal amount and it rotates. I tried to copy that heres a code for that:

Code (CSharp):

1.  
2. isGrounded2 = Physics2D.OverlapBox(groundCheck.position, new Vector2(1.08f, 1.58f), 0, groundLayer);
3.  
4.  
5.         //This is a lambda expression it basically means if absolute value of players rigidbody veloicty x is bigger than whatVelocityToMultiply(its 12) jumpMultiplier variable is 1.7f same thing goes for other one altWhatVelocityToMultiply is 9
6.  
7.         float jumpMultiplier = (Mathf.Abs(rgbd2d.velocity.x) > whatVelocityToMultiply) ? 1.7f : (Mathf.Abs(rgbd2d.velocity.x) > altWhatVelocityToMultiply) ? 1.3f : 1f ;
8.  
9.  
10.         if ((Input.GetKey(KeyCode.Space)) && (rgbd2d.velocity.y <= 0.01f) && (isGrounded2) && (relativeCheck.relativeVelocityCheck))
11.         {
12.             jumping = true;
13.             rgbd2d.AddForce(forceDirection * jumpAmount * jumpMultiplier, ForceMode2D.Impulse);
14.             Debug.Log(jumpMultiplier);
15.         }
16.  

This void method called on FixedUpdate

Here is a video explanation for this (I slow down the part for better understanding)

I looked up about AddForce inconsistenty but i couldnt found anything useful

 

Even if i have all constant variables still has the same problem, sometimes it jumps very very little as if its bouncing

 

But i found a important part about this bug on my game, it happens every time i tried to jump on the sides maybe it has to do something with PlatformEffector2D that i use for one way platforms