The Yellowstone Anomaly is an astral rift that connects to the fae metaplane that is home to the Seelie Court. It was opened after the events of the Yellowstone Calamity. It appears to be unstable, vanishing without a trace only to appear back at a whim sometime later. It does appear to be drifting eastwards.
Renraku appears to have been successfully exploring the metaplane and even setting up some trade with the Seelie Court. They have started to sell food from the fae metaplane and branding it as real food.