This is the exact problem. In the comics the Manhunters are ancient, unstoppable androids that wiped out entire sectors and forced the Guardians to create the Green Lantern Corps as a replacement.
Green Lantern The Animated Series actually showed them as a terrifying, relentless army. This show has John being ‘shown the threat’ and the audience just gets an old lady and more talking. By episode 6 the rings, constructs, space, and the actual mythology still exist only as exposition. At that point just drop the Green Lantern branding and make another prestige small-town crime drama. Using the IP while refusing to visualise any of it isn’t clever restraint, it’s just cheap.
This scene from Lanterns episode 2, sums up everything wrong with this show:
John is shown the threat of Manhunters, but WE never see it. We just see an old lady. We’re at ep 6, and almost every cool sci-fi element exists only in dialogue. There’s no excuse...
Show, don't tell.