Zenless Zone Zero's hidden flying city of Roscaelifer was made entirely to support the computation of the Rosetta Data, the master copy used to recalibrate and cross-check all Hollow data.

Hollows are a sub-space outside of our reality, black marbles dotting the landscape where reality and physics break down inside them. They twist and turn constantly, the way in is never the way out- if you come unprepared without a Carrot, you WILL die. If the Ethereals don't get you first, existing inside them for too long will painfully kill you and turning you into an Ethereal. If you stay too long in a Hollow, you may fall victim to Corruption as a disease, which can range from Ether sensitivity, to a wasting disease that will one day horribly kill you, just not turn you into an Ethereal, as they cannot exist outside Hollows.

Hollows are everywhere, most of the planet has been consumed by Hollows. The only way to stop a hollow is to kill its core. A Hollow that grows enough may spawn Companion Hollows, which may mature enough to become its own Hollow, perpetuating the cycle.

Roscaelifer was made with Bangboo in mind (little bunny robots) who are all needed to assist in the computation of the Rosetta Data. Without them, the Rosetta Data may be incomplete, and the exploration and defense of the Hollows grinds to a halt.

The Data that the Bangboo compute is inherently corrupted, and have an actual, permanent effect on them, killing them or worse. To combat this, Roscaelifer "retires" Bangboo before this happens, wiping their mind and sending them down to New Eridu, "The Last City On Earth", where Bangboo are considered expendable and disposable.

Morality of creating data-scraping robots and a city where they live with equal rights to humans, and then when the hazardous data threatens to brick them, mind-wipe them and send them down to another land where they have less rights?