I hate poison gas vents that pointlessly litter every dungeon, but I can live with it. Now the devs found a way to shove gas vents in the underdark too?!
Why?
How?
It is a pointless, uninteresting mechanic. It is not fun. Obstructing a gas vent with an object to get around it is an annoyance at best.
Please, devs, restrain your poison gas vent addiction.