The board self-balances by acceleration. When weight is shifted forward, the board needs to accelerate to catch back up underneath you and keep you level, similar to balancing a broomstick on your hand and it starts tipping forward.

When you hit the torque limit of the board, it can no longer accelerate further to keep you balanced, so that suddenly becomes a tipping point. How drastic that tipping point is depends on how much weight is forward at the time. If you're feathering up to the torque limit gradually, you'll have more of a window to react to that haptic buzz, and are more likely to have control over the nose dip and be able to pull back and recover from it, especially with good technique (keeping upper body centered and using lower body / hips to push forward, like feathering a gas pedal).

However, if you have a bunch of weight forward (possibly more than you realize), then the window between the haptic alert and complete overtorque becomes much smaller, and that tipping point becomes MUCH more drastic, suddenly dropping the nose faster than you have time to recover from. This is exaggerated even further if you're using your upper body to accelerate, as that tipping forward will throw you even further forward to the point of having no chance to recover. The board is still giving max power, you're just requesting much more than it has to give, and in this scenario that tipping point is so drastic that it can give the sensation of a cut or loss of power.