Grenade will cause abnormal damage when it is thrown at a enemy directly

When a frag grenade is thrown directly at an enemy, it should cause 2 damage. However in some specific situations, when the grenade lands on an enemy, it will cause damage per frame. The two video clips provided demonstrate these two different scenarios. As you can see, in the second video clip, the grenade caused 5 damage instead of 2. In the first video clip, the grenade correctly caused 2 damage.

I don't think this is caused by the grenade bouncing between multiple enemies, resulting in more than 2 damage, because during gameplay, I encountered a situation where a grenade hit an enemy and continuously dealt 100 damage before exploding. I am currently trying to make this issue reoccur.If I succeed, I will upload a new video clip immediately.