Why does Batman sometimes lose about an eighth of his health when I do a silent takedown from behind?

This is my first time playing Batman Arkham City (GOTY), and the series as a whole (beat Asylum yesterday and today i started City) but I have lurked on this sub reddit for years. But as I was playing (currently doing the mission where you need to rescue Freeze from Penguin and I’m destroying the signal disrupters) I noticed that I lost a tiny bit of health affer performing a stealth takedown on an enemy from behind. I’m not sure why this is happening and my friend who has played the game doesn’t know either.

• I payed for the game and have it on Steam so it’s not any kind of anti-piracy I don’t think

• I have installed several suit mods and reshade (I don’t think thats the issue)

• This happens at random not every takedown but I have not been able to figure out a pattern. It’s happened on enemies with guns, unarmed etc so this makes it difficult to replicate.

I was hoping someone could give me any advice? It’s not the biggest issue in the world and it doesn’t really affect me but I’m curious to see if anyone has experienced anything similar/knows why this is happening. Thank you :)