I mean, it literally has a gravitational pull, as seen with the spinning onomatopoia in the background and the buildings in the background being pulled in.

The only real alternatives that someone has pointed out is dark matter. But... the problem is that dark matter is invisible. It doesn't interact with light at all. So Dark matter wouldn't fit the description of a black "ball."

I've even seen people say "dark Energy", which is just really bad guessing. Just because it has dark in its name doesn't make it a good canditat. The known attributes for dark energy are that it somehow expands the universe. So, it's not really fitting of making a black circle with a gravitational pull.

Others just say that's its "darkness." My problem is that it's too vague and also doesn't fit what we see. Darkness doesn't technically exist, and it doesn't have mass or a gravitational pull like dabura's CTR has.

Something important to note is that dabura doesn't even have to apply his mass giving technique as seen with Picture 2. it's a separate CT that's manifested as his horns. 

Im saying this because people have said this as a way to debunk it being a black hole since a black hole can't have "anti mass" funnily enough these people will then say it therefore his has to be anti matter, but the problem is that anti matter also has mass.

But yeah, everything shown to us in the manga fits the description of a black hole. Someone may then say that it doesn't make sense for what dabura's CT is, but that isn't necessarily true.

Dabura's CT is light that he can projecte and shoot. It makes sense that his CTR is then something that pulls in that light instead, aka a black hole.

"But how can he survive being so close to it?" sorcerers can generally control their own ct. I mean for god sake yuki's will could control her larger black hole from the fucking dead. Even then, dabura can move at near light speed, so I doubt the gravitational pull from the black hole is all that for him.

What are people's reason for claiming this isn't a black hole?