I’m not suprised the grenade buff was devastating on this monster.
In the old versions sometimes i just left the breathers behind because it was impossible to kill them without a good weapon.
It seems you didn’t miss the artifact, i looked deeper into the code, they added the anomalies to the labs but without the artifacts, it is called "portal with an artifact effect ". So the breathers will be more common in the game because anomalies are more common, but artifacts are still rare. Only surface anomalies have an artifact.