Trying to get aiming on 2d game consistent

When testing my game I noticed that with the code I have below the bullets lose their randomness the closer I aim my mouse to the right. Note

void Shoot()
    float bulletDrift = Random.Range(-variance, variance);
    Vector2 bulletTrajectory = new Vector2(this.transform.right.x + bulletDrift, this.transform.right.y);
    BasicBullet bullet = Instantiate(this.bulletPrefab, this.transform.position, this.transform.rotation);