When you drown and respawn, your air meter doesn't instantly get set back to normal, instead it has to regenerate up to max, this means that you can instantly start drowning when you respawn in water.
When you drown and respawn, your air meter doesn't instantly get set back to normal, instead it has to regenerate up to max, this means that you can instantly start drowning when you respawn in water.
Fixed in 1.13-pre2