Rigidbody player controller on moving platforms

So basically, I was trying to make moving platforms. When I finished my prototype, I noticed that the movement on the platform is very wobbly:
https://www.youtube.com/watch?v=hmBumsrlHGA&feature=emb_logo
To snap the player onto the platform, I am just making it a child of the platform. Anyway, I don’t know what is causing this issue and was wondering if I can get any help. Thank you in advance

Here, the controller code:

private void Movement()
    {
        //Extra gravity
        rb.AddForce(Vector3.down * Time.deltaTime * 10);

        //Find actual velocity relative to where player is looking
        Vector2 mag = FindVelRelativeToLook();
        float xMag = mag.x, yMag = mag.y;

        //Counteract sliding and sloppy movement
        CounterMovement(x, y, mag);

        //If holding jump && ready to jump, then jump
        if (readyToJump && jumping) Jump();

        //Set max speed
        float maxSpeed = this.maxSpeed;
        if (sprinting)
        {
            this.maxSpeed = 25;
        }
        else
        {
            this.maxSpeed = 15;
        }

        if(sprinting && y < 0)
        {
            this.maxSpeed = 15;
        }

        //If sliding down a ramp, add force down so player stays grounded and also builds speed
        if (crouching && grounded && readyToJump)
        {
            rb.AddForce(Vector3.down * Time.deltaTime * 3000);
            return;
        }

        //If speed is larger than maxspeed, cancel out the input so you don't go over max speed
        if (x > 0 && xMag > maxSpeed) x = 0;
        if (x < 0 && xMag < -maxSpeed) x = 0;
        if (y > 0 && yMag > maxSpeed) y = 0;
        if (y < 0 && yMag < -maxSpeed) y = 0;

        //Some multipliers
        float multiplier = 1f, multiplierV = 1f;

        // Movement in air
        if (!grounded)
        {
            multiplier = 0.5f;
            multiplierV = 0.5f;
        }

        // Movement while sliding
        //if (grounded && crouching) { multiplierV = 0.5f; multiplier = 0.5f; }

        //Apply forces to move player
        rb.AddForce(orientation.transform.forward * y * moveSpeed * Time.deltaTime * multiplier * multiplierV);
        rb.AddForce(orientation.transform.right * x * moveSpeed * Time.deltaTime * multiplier);
    }

void Start()
    {
        rb = GetComponent<Rigidbody>();
    }
void landOnPlatform()
    {
        rb.isKinematic = true;
    }