In Dragon Ball, all saiyans have white/transparent ki with the exception of Vegita in a few chapters of Dragon Ball Z where he had light blue ki, and Goku Black who had black/violet/transparent ki before transforming into super saiyan Rose. What is Cumber red ki about then? is Cumber red ki his regular ki or is it a transformation?
The Dark Aura which surrounds Kanba here is just his ordinary ki which is supposedly considered to be a dark evil Ki. if you look at the Dragon Ball Heroes Universe Mission 3 trailer, you can see Kanba as a Regular Super Saiyan at the 0:09-0:10 second mark.
Hence it is fair to assume that is Kanba's ki in his Base form. I have also attached an image of the same below.