Looks like I slightly misremembered. They write that they don't observe a decline of inhibition compared to a previous paper using pure bromoform but don't speculate on the reason. Maybe the speculation was in commentary on that paper.
This suggests that the mechanism is not totally understood, which is easy to understand. It could require either tertiary agents in the seaweed/gut microbiome interactions..
Looks like I slightly misremembered. They write that they don't observe a decline of inhibition compared to a previous paper using pure bromoform but don't speculate on the reason. Maybe the speculation was in commentary on that paper.