First wipes tips

[Niwashi]

Tanks health 1 hit and as all the DPS health was massively dropping fast.

That pattern sounds like the result of a mechanics failure. For that particular fight, it would most likely be from not moving the boss out of the poison pools. (That's primarily the tank's job, but anyone who gets targeted with the poison also needs to help keep it confined to the side so that there's a clear spot available for the tank to move Aiatar to.)

they kicked the tank and got a new tank and finished it in 1 go so I'm not sure if it was me or the Tank

If replacing the tank fixed the problem, that's further confirmation of where the problem was.