"Immune to Poison"

I get that its "poison" but what is the point if "caustic ground" which is a giant green pool on the ground... The icon for the debuff is a bright green droplet... but hey "immune to poison" doesn't mean immune to the giant green pools on the ground because its "caustic" not poison.

If its chaos damage over time, make it purple pool and a purple debuff icon like every other chaos damage thing in the game and then... immune to chaos damage does purple stuff and immune to poison does green stuff

I understand that poison cloud is the actual poison ground effect, but the point is still clarity. Immune to green should mean immune to green... not some of the green but not all of the green.