SRAM replacement dub crankset, is this pre-greased?
Yes that is grease, in my opinion that is about the bear minimum amount intended to help prevent seizing between the two interfaces. I usually leave it if it is my own bike and just add a bit more additional grease, as most cycling greases will not have any interaction with each other. In a professional setting or working on someone else's bike I would remove it and use all one type.
If you watch Sram's installation videos they are definitely a bit more liberal with the application spreading it both on the exterior of the spindle, and in the grooves that interface with the crankset.