Boss Rush Power Struggle (Invisible woman.) Question

Anyone can explain to me why the power struggle node, in boss rush, don't give a full bar of power???
Is it because of any of Invisible Woman's ability???

5 sec in video. IW gets a bar, and, I get a portion of it.
https://youtu.be/HApYmg2YxQQ
Is it because of any of Invisible Woman's ability???

5 sec in video. IW gets a bar, and, I get a portion of it.

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Comments
"When Attacked:
If the Force Field is active, 65% chance to Exhaust the Opponent, decreasing Critical Damage Rating by 58.25 for 5 second(s). The Opponent's Power Gain effects are also reduced by 25% for each Exhaustion Debuff on them."
So once you have 4 exhaustions you won't gain power.