There are many factors that can go into this. It will depend on the opponent and your stats. The reason why players from the community are talking about the stats that surround critical hit is because that can play a part in the damage.

Just to go over some information:

Critical Stat: Increases the rate of a Critical Hit and reduces the rate of suffering a Critical Hit (this is strictly the chance you can give or take a Critical Hit)

- By doing a critical hit, you do an increased amount of damage.

Injury Stat: Increases a Critical Hit's Damage or reduces a Critical Hit's Damage.

- This stat influences the amount of damage dealt, the more the injury stat is higher than yours, the more damage an opponent can do to you. This will be based on your opponent's ninja's injury stat and the respective ninja you have that is taking the hit from Kushina Red Hot-Blooded Habanero.

Many things can @lso be taken into account to do more damage. Other stats could be Taijutsu and Ninjutsu Pen3tration, which at low BP doesn't do as much, but can account for some damage. Also remember that each ninja has inherently their own specific growth stats (base stats) and this can @lso take into account. It could so happen that the ninja you had was more susceptible to damage, however, without more information as to the level between you and opponent, battle power difference and more specifically, the ninja stats involved, it is just theory. Hopefully this helps.

~Jib

Jib Edit: Had to edit to avoid censorship xD