Is movement line of Subs visible?

I am adding a picture showing the very minimum, not to give myself up accidentally as I'm still in the game.

I have a Sub moving, and suddenly the enemy matched my destination point. There is no point of interest for the enemy around this area to move here. Is it just a coincidence or is Sub movement line actually visible?

Screenshot 2023-11-15 at 14.37.35.png

Could it actually be that a Balloon stationed nearby is revealing the part of the movement line visible in it's range?