Does landscape material index-0 have any special role/purpose?

Hi, I posted a question last month about an issue I have with landscape material index-0 but I never got an answer.

So now I am wondering if the explanation of this issue is because this material index-0 has any special role/purpose different then the other landscape material indexes. I had set its option to be the default material for the whole landscape.

Does it or it is the same role/purpose/attributes as all other indexes for the UE5 game engine?