I'm not really getting what makes this a world first?

Controlled deorbits have been a thing for a while, and if we're talking about deorbits designed to minimize risk of debris impact, IIRC Starlink satellites were designed to maximize the amount of the satellite that is vaporized by reentry.

Edit: Ah, the "world's first" is that they were able to choose where any parts that aren't vaporized would crash. The esa article is clearer on that.

I guess if I were to be unnecessarily pedantic, most crewed capsules and reusable ISS resupply vehicles have also technically done that.