This is the first time Ive ever seen this.
It's a weird residue in the blow of container' where the gas comes out of the hose and hits the glass.
It looks like 'smoke soot' , for a lack of a better description.
Also, there is NO liquid coming from the tube, only gas.
The container has starsan in it. It's been in there for one week so far, but only noticed this after about 4 or 5 days
This is my first lager, a Munich Helles ( could that have anything to do with it?)
I have done plenty Ales in this conical into this growler and never seen this.