Even if you assume the treadmill is somehow able to match theoretical speed exactly, eventually there won’t be enough friction between the wheels and treadmill to hold it in place - you’ll get wheel slippage, the plane will start to move forwards due to the thrust exceeding the forces that the wheels/treadmill can cope with and it’ll begin to generate lift.
Or the wheels explode and the plane is catapulted backwards off the runway for everyone to be killed in a fireball.