Bug Rigidbody2D.MovePosition behaving differently between editor and build (PC)

(I apologize if my english is a bit broken)
Hello!
I need help for a problem with RigidBody2D: I have a script called Entity that contains the following FixedUpdateMethod:

Code (CSharp):

1. public virtual void FixedUpdate()
2.     {
3.         velocity.x = Mathf.Clamp(velocity.x, -maxVelocity.x, maxVelocity.x);
4.         velocity.y = Mathf.Clamp(velocity.y, -maxVelocity.y, maxVelocity.y);
5.  
6.         rb.MovePosition(velocity * Time.fixedDeltaTime + (Vector2)transform.position);
7.     }

and a PlayerController script that override FixedUpdate:

Code (CSharp):

1. public override void FixedUpdate()
2.     {
3.         velocity.x = Input.GetAxisRaw("Horizontal") * speed;
4.         base.FixedUpdate();
5.     }

The problem is that the player doesn't go at the same speed between the editor and build version. In the editor, velocity.x * Time.fixedDeltaTime as a value of 0.2 and the difference between transform.position.x and the transform.position.x of the last frame is always equal to velocity.x * Time.fixedDeltaTime. But in the build, velocity.x * Time.fixedDeltaTime as the correct value of 0.2, but the difference in x position between two frames switches back and forth between 0.2 and 0.1.

I also checked others variables that could cause a problem like this (like Time.fixedDeltaTime, speed, rb.drag etc.) but they all are equal between the two versions.

I searched for a good hour on google and by experimenting but couldn't find anything so i don't know if i just haven't seen an evident error or if it's a bug in unity...

If you need more informations don't hesitate to ask them (it will surely be the case because i'm not very good to provide them ^^)