I can't see the video since it keeps telling that I lose connection but, I guess it is due to her skill 3.

Designer Lilibet reduces debuff duration by 2 so it is not a true cleanse. Bombs go boom once the duration ends.

it’s kinda hard to see in the video but the duration of the bomb debuff doesn’t change either. And her bombs are only two turns so they should be erased after lilibets cleanse, but instead nothing happens at all. 

The Answer to your inquiry in two images

reading tooltips is hard. maybe if people did it more they'd be here less.