cant freeze rotation or set it manually to 0 on Zombie Model, Freezing or setting rotation not working

I have a Zombie Model, where i have a Rigidbody attached and that Moves Towards me and Attacks me.
But it rotates around the frozen X axis and even if i set it in the script with every possible answer, it doesnt work

public void FixedUpdate()
    {
        transform.Rotate(0, transform.rotation.y, transform.rotation.z, Space.World);
    }
    // Update is called once per frame
    void Update()
    {
        DistanceToPlayer = Vector3.Distance(transform.position,player.position);
        if(DistanceToPlayer < safeDistance)
        {
            transform.LookAt(player.position);
            transform.Translate(new Vector3(0, 0, 0));
            if (canAttack == false) return;
            ZombieAnimator.Play("Attack");
            Invoke("Attack", 2.0f);
            canAttack = false;
            if(Health.playerarmor > 0)
            {
                Health.playerarmor -= 10;
            }
            else
            {
                Health.playerHealth -= 15;
            }
        }
        if(DistanceToPlayer > safeDistance)
        {
            transform.position = Vector3.MoveTowards(transform.position, player.position, movementspeed * Time.deltaTime);
            transform.LookAt(player.position);
            ZombieAnimator.Play("Walk");
        }
    }
    void Attack()
    {
        canAttack = true;
    }

By putting that line into FixedUpdate:

transform.Rotate(0, transform.rotation.y, transform.rotation.z, Space.World);

It won’t stop the transform from rotating around the X axis. Setting Rigidbody.constraints to RigidbodyConstraints.FreezeRotationX will do that.