Ahh. Thanks very much good person. That needs to be explained more thoroughly in the tooltips. A simple "this effect will alert enemies" would be nice. Thanks a lot. Basically if you want to go stealth avoid some of the legendary ones. Now it would be awesome if you craft more than one quickhack instead of the lesser versions disappearing after you craft one. Now I have a real need to have copies of the epic versions. Although that would be a hassle and a half to have to switch out quickhacks constantly.Ping, Optic Reboot or System Reset don't by their own. But "combined" with passive effects from other legendary QHs which alert enemies (like cripple movment), they can. Not by their own, but because a passive effect is also applied afterward by other legendary QHs.
For example :
Legendary Cripple Movement > Passive while equipped: enemies under the effect of any quickhack cannot sprint.
So if you use Ping, which obviously apply a QH effect on all enemies, Cripple Movement passive effect will also be applied at the same time and enemies will be alerted.
The same for :
Sonic Shock > Passive While Equipped: enemies under the effects of any quickhack are cut off from the local network, preventing them from communicating with their allies.
So if you play stealth, be sure to unequip all the "offensive" QHs which add additional effects automatically.