This might be Three Bodies at Mitanni by Seth Dickinson. It was written in 2015 and has been published in several anthologies.
It is set in a future after seedships had been sent out from Earth to colonise other planets. The protagonists are Anyahera, Thienne and Shinobuthe, who are the crew of the spaceship Lachesis. Their task is to find the colonies and destroy them if they judge them to be a threat to Earth.
In the story the crew have just found the colony planet Mittani. This is a very harsh planet as you remember. The records show:
I saw the seedship’s arrival on what should have been a garden world, a nursery for the progeny of her vat wombs. I saw catastrophe: a barren, radioactive hell, climate erratic, oceans poisoned, atmosphere boiling into space. I watched the ship struggle and fail to make a safe place for its children, until, in the end, it gambled on an act of cruel, desperate hope: fertilizing its crew, raising them to adolescence, releasing them on the world to build something out of its own cannibalized body.
To survive the colonists formed a hive mind where the sacrifice of individuals is of little consequence, and this is judged to be a Duong-Watts malignant and a danger to Earth. In the end the colony is destroyed, but one individual is saved to allow the species (the Mittani are treated as different human species) to be recreated one day.
“Here are our terms,” I said. “We will annihilate the Mitanni colony in order to prevent the explosive colonization of the Milky Way by post-conscious human variants. This point is non-negotiable.”
The Mitanni ambassador waited in silence. Behind her, Thienne blinked, just once, an indecipherable punctuation. I felt Anyahera’s grip tighten in gratitude or tension.
“You will remain in storage aboard the Lachesis,” I said. “As a comprehensive upload of a Mitanni personality, you contain the neuroengineering necessary to re-create your species. We will return to Earth and submit the future of the Mitanni species to public review. You may be given a new seedship and a fresh start, perhaps under the supervision of a pre-established blockade. You may be consigned to archival study, or allowed to flourish in a simulated environment. But we can offer a near-guarantee that you will not be killed.”
