I imagine they should steer to the right, as more passengers sit on that side? Are these planes manufactured differently (non symmetrical wings)?
The effect of the passengers on balance is much less than the effect of fuel load. An A220 can carry around 17 metric tons of fuel, which weighs more than 150 average passengers and is at a much higher lever arm than the passengers.
Any imbalance would cause the plane to roll slightly if the ailerons were kept perfectly neutral. But this is easily counteracted by a little aileron trim.