I had the same problem (minus the delimitation).
After very careful inspection of the shower framing I took it upon myself to fix the issue myself.
The root cause (I had to dismantle the shower frame on my 2017 to determine root cause) is that airstream do not adequately seal the frame, the sil / threshold and the various joints.
The discharge you see in your shower will turn dark brown soon in is actually rust which you will see in my pictures - which comes from a small screw behind the frame that holds down the sil to the plywood framing.
Water gets behind the frame on the sil at the bottom corner of the door and can then leak out damaging the plywood that the aluminum sil sits on (you are seeing the effects of this as a delimitation problem).
The solution is a lot of clear silicon caulk.
I re-calked both sides of the shower frame/fiberglass and frame/sil junction from the outside. I then removed the lower screw in the framing (accessible from inside the shower, pictured just above my finger in the attached picture) that holds the door to the frame. I then injected A LOT of silicon own into the frame structure, allowing it to accumulate inside the frame at the bottom, further sealing the area from the inside.
Below is a picture of the silicon product you will want to use. I chose the clear version (one in the photo is white). Available at Home Depot. I have photos of the repair and somewhere... I will try to find them for you.
I did not trust the dealer to perform this repair to the quality / level of satisfaction I was looking for.
In the end it took me about 4 hours to take things apart, find the problem, determine the solution, re-assemble and then caulk the framing.