The dark card recites: "Play when Rachel uses a Cyberware card. She must either spend $ 1000 or discard the Cyberware card. If she chooses to discard it, the Cyberware's effect still takes place".

I suppose "uses" means "activate a Cyberware card that Rachel's player has in front of him/herself".

But I don't see the point of playing this card against Rachel if she can discard the card and have the effect take place as well.

Maybe it's only worth against those cards that have a continuous effect and not "one-shot" Cyberware cards.

There are only 5 Cyberware cards; 3 have a continuous effect, and the other two are:
Poison Gland: discard it to place a hit on a suspect
Painkiller Gland: discard it to discard 4 trauma

If I play the dark card "That Cyberware seems to fritz" against the Poison gland (as she tries to use it) and Rachel decides to discard it, and the effect takes place, means that the dark card affects only 3 light cards.

 This has already been answered for you on BGG.

Sorry, I wanted to hear if someone had a different opinion.

I won't cross-post anymore.