How about not having legends with F tier abilities going up against S tier?
How hard is it for you to walk out of floaty green stuff?
How hard is it for you to not notice big red balloons the size of wraith?
How hard is it for you go disable these traps by shooting its weak point?
If you are getting stomped on by stationary DPS, the problem isn't the gas - it's you.
Either you're camping a building or,
You're rushing a building without thought or,
You're just trying to contend in a gaseous field.
If you say no to any of those, gas isn't a problem for you, and it didn't need a nerf.
If you say yes to one of those things, try not standing in the fire. It's a game mechanic that's existed since the 80's.
Cool?