With phoenix ultimate teleport with low grav, even though you fall slowly after your teleport, you still take the fall damage even though you are low gravving to the ground.
This occured on nuke, teleporting from t side to ct side to go underground via the stairs. This might be a teleport damage that isn't dealt until you land? I will try this more on other maps.
Ok so i think that the issue is not the low grav, but the time the low grav stays available. if you are still in air from a long teleport and low grav skill goes away, then you will take the fall damage from that point forward.