First, I advise a modicum of skepticism to be retained in the face of such news. Ukraine is, after all, in the middle of an existential crisis and must take every advantage it can, even if it's just scaring Russian invaders further (I bet both Russian and Ukrainian soldiers are already pretty scared of drones).
Additionally: "“There is no connection to the drone at all, you cannot see the video, nothing…". So there's no way to know exactly what happened which adds a lot of uncertainty.
Finally: the system was first used two years ago once, then never again. That doesn't sound like it's giving much of an advantage. Sorry, I don't believe that it's a matter of military ethics. If Ukraine could deploy actual Terminator robots to the front line it would do it in a heartbeat. Again: existential crisis. They're fighting for their country's existence. I would use every weapon in my disposal; and I'm a pacifist who hates violence. So I don't think that "test" really worked well at all.
Now, taking the New Scientist's reportage at face value, the announcement seems to describe a system that is only marginally more capable than a self-guided missile. It seems that a quadcopter swarm of undisclosed strength flew to a predetermined location (nothing new to see here), then a target acquisition system was activated.
Is the latter a new capability? Hard to say without more details that we're not likely to know. Maybe the drones simply locked on to whatever moved. Motion sensing is not new technology. Nor is it a great idea to put it on a flying grenade that you fire-and-forget.
Maybe the drones had some on-board machine vision system that tries to identify useful targets like persons and vehicles. That's eminently possible with modern tech, I have a Raspberry Pi-powered quadruped from China that can detect my face, identify balls of different colours etc. All this is more than enough to automate target selection, with a bit of creative cobbling together of existing components and if you don't care too much who the target selected, is.
Without more information it's very hard to guess exactly what happened. However, "Slaughterbots" these don't seem to have been.
Later, a different, human-piloted drone was sent in to inspect the outcome. Why human-piloted? Well, because there's no way to ensure that an autonomous drone will be able to do the job, that's why.
So in other words: we're not there yet. "There" being a nightmare where machines kill humans autonomously and we unlock a new level of horrors and war crimes. There is still time. We can still pull back from the brink. Resistance is not futile.