Yep, which is why we're scratching our heads here. Because they've apparently got a perfect counter to the sensors we use on literally every ship at our disposal to the point of effectively having a Combat Cloak, but civilian sensors and Member Fleet ships are still perfectly capable of resolving them.
Top level infiltration (or defectors from top level clearance) is the best explanation for what happened here, because the alternative are that they're literally wizards on a level that make the Mentats look positively tame (Because the Mentats were more likely to blow up in their own faces then come up with something mass producable.)
Of course, another possibility is that they got their hands on a sensor-specialist Mentat and that's how they've got such a ludicrously powerful effect that still fails absolutely outside of a very specific target grouping.
This is of course a probability, but I'd dispute that it's the most likely explanation.
When would Konen specifically have the time and resources to either place a mole in Starfleet, or recruit someone with technical knowledge required for such go-around? Why them, and not Cardassians? If it had been a joint Ashalla Pact op, why are only Konen ships displaying these characteristics? You'd think with how much attention we had put on our internal security (in no small courtesy thanks to Syndicate) we would have noticed
something. This is why I in particular think defection is unlikely. Linderly or someone else would have likely noticed a person with high clearance suddenly disappearing. Recruiting an internal agent would be more likely than that.
But if that was the case, then the Pact would have screwed up by wasting their hand and showing us what they're capable of, unless we're facing imminent invasion, since the value of moles lies typically in their ability to feed you constant information, thus dispelling the proverbial fog of war.
It could be that the latest nomadic species has provided them with some gizmo that spoofs our latest sensors for some highly specific technobabble reason. It could be that Konen mindjacked information out of
Republic prisoners and found a specific flaw only they could exploit. It could be some form of ECM Konen had well in advance, but we never saw it in action etc. There are any number of scenarios that are equally likely, use consistent logic and fit the evidence we've seen so far.
However, this does raise us a question: are we still confident in our approach to Ashalla Pact? Because frankly after recent events, I don't think "we will sit back and drown them with ships" will actually be as effective as we think it's going to be.