Again, I just want to clarify.
Hacks exist for IronSight. Hacks are available to use for IronSight. Hackers exist in game. At least, they did. I don't know if any are still around, especially due to diminishing player counts. I'd wager that those who hadn't been banned for cheating, most likely don't play anymore.
Back in February-April 2018, when IronSight first really hit the public eye with larger mainstream youtubers showing off gameplay of IronSight, that is when the most hackers were around. Since then, it's died off.
The only problem is finding out who is actually cheating, against the serverside issues IronSight already has. Who is hacking, and who is actually just a victim of poor netcode
My opinion, if you do like crazy mods and you do it in private match’s, your fine, but if you endanger the players exprience in game that actually hurts the player base