How do you ban "technology"?
To ban something, they would first need to be able to identify it. They would need a pretext, however flimsy, for why these artifacts are banned. Someone knows what it is, or has a good enough idea how it works, to create a law and enforce it.
Human beings would not become so stupid as to "forget" what a metal is, or that knobs are mechanical creations. Even stone age people would know it didn't come out of a cow or a plant. Suppose they have lost the knowledge to smelt bronze, they would have soft metals like copper and gold. These metals could be scavenged from ruins, just as Egyptian tombs were scavenged for precious metals thousands of years after the society that created them were gone.
Clarke's Third Law
You have a MacGuffin that is controlling events in the story. It doesn't matter if it's magic or from outer space, that reveal isn't some "twist" to the plot. It is obviously foreign and anachronistic to the setting. This won't be a surprise to the reader, at no time will they assume it is just a magic pumpkin up until the reveal it has knobs and wires. It's Clarke's Third Law: Any sufficiently advanced technology is indistinguishable from magic. It makes no difference.
"Technology" is ridiculously broad. A society that banned all technology would ban farming and weaving. They would die because modern humans only evolved with the help of technology: stone blades, fire, and leather-working. Humans that keep livestock have rope tethers and fences. Without technology, humans are far too weak to hunt for meat, and without meat humans cannot support a calorie-hungry brain.
You have a world-breaking premise. Fix it with worldbuilding and characters
You have a world-breaking premise so fix it. SOMEONE knows what "technology" is, and they have enough of it to enforce that no one else has any. Your discovered artifact is taboo, evil, ungodly – all the scriptures say so. These artifacts were once everywhere and they poisoned the people until the Praetors® were established to rid the land of these horrible things. Now we live free from the evil, but if you see an artifact you must tell an elder who will contact the Praetors® to come and cleanse the land. This gives you an antagonist.
Someone has found the artifact, and of course it is an artifact what else could it be? But the person who found it is not always someone who follows the rules. Maybe they are greedy and believe the artifact will make them rich. Maybe they came from a village that was "cleansed" by the Praetors. Maybe there are rumors that the artifacts can heal sickness and disease. Maybe the village well has become polluted with human waste, and the artifact gets dropped into the well to purify the water, it kills the microbes but eventually poisons the village. The point is you need a protagonist who believes they are doing the right thing by keeping the MacGuffin from the antagonist.
The conflict needs to be between characters who have mutually exclusive goals.
Don't give an inanimate object all the stakes in your story. The only way to raise the stakes for an inanimate object is to reveal its origin or to increase its power, presumably things you plan to happen anyway. There is no internal conflict or decision to be made. There is no "twist" to reveal – again, Clark's 3rd Law says the distinction between magic and technology in this scenario is meaningless. Withholding this information doesn't raise the stakes. It might be a curiosity for the reader, but it doesn't change anything for the characters.
MacGuffin's aren't characters. They get a special word because they aren't meant to be examined up close (the origin is a box with nothing in it). MacGuffins tend to fall apart when taken too literally. Instead MacGuffins are elusive and mysterious. You have a taboo object which is banned. Maybe your protagonist isn't comfortable looking at it directly. Maybe it is scary to contemplate so many unanswered questions that go against the scriptures. Maybe it's kept wrapped up and hidden, so those knobs and wires aren't so obvious. Think about it – if you found a demon's head in the woods, would you bring it home and prop it up on the mantle, or would you keep it hidden in a box in the garage?
Don't rely on this "reveal", it can only feel important if it somehow changes things for the characters. Instead you can describe its "strangeness", emphasizing how it makes them feel (frightened, ashamed, greedy). None of the characters would give such a loaded object neutral descriptions. In addition, the various opinions would escalate as the artifact's influence spreads, creating division as everyone sees it as something different, filtered through their fears and biases. If it was sinister before, it becomes menacingly evil. If it seemed like an opportunity for profit, it will shine like gold. There should be no neutral or objective description of the object. The reader is never sure what it is. The important thing is what it represents, and how each character reacts.