It seems like every hit is adding at least 1 point on vertical force.
There is a code segment inside ControlsScript.GetHit that checks if the character is over their crumple limit. If they are, pushForce.y is set to 1 so the character instantly falls down:

if (consecutiveCrumple > UFE.config.comboOptions.maxConsecutiveCrumple) {
      isKnockDown = true;
      airHit = true;
      pushForce.y = 1;
}

Look and see if you changed any of those conditions.

Looks like we found the issue...it was in the Physics script. We were able to patch the problem but it only works  if the players transform Y position is at 0.  Just allowing the player Y position to go beyond or below 0
when the player goes beyond or below 0, this is when the player breaks and the stun feature stops working causing the player to immediately fall once they are hit.