Rear black tank confusion with monitor panel lights which read gray#2

I have a 2020 Momentum 29g.
After several calls to customer service, I still am not clear on the gray#2 water indicator lights that I have confirmed are monitoring the black tank for the rear bathroom.
Customer service says the indicator for gray#2 is monitoring the rear black tank.
It is very confusing that the black tank has a black tank label on the outside dump handle.
Why not call the gray#2 black#2 on the monitor panel?
I have also confirmed that if you drain the rear black tank and add nothing to it at all, you will somehow get gray water in this tank.
I can only deduce that the main gray tank is moving water to the rear black tank.
I just need some answers to why it is so confusing that the monitoring panel lights say gray#1 and gray#2.
Does anybody out there have some answers without guessing?