Need Help!

I was replacing my DISA and my lower intake boot for regular maintenance and well, I'm pretty amateur and found an insecure line but i have no idea what line this is or what it should look like but it comes from behind the Brake Fluid Reservoir and down behind the DISA valve and as you can see by the overly large picture, it's loose and can come in and out with ease.





Any help would be greatly appreciated.