Either I can’t read, or they need an editor. In your excerpt the article contradicts itself at least twice.
If you're referring to "tiny galaxy" and "ultracompact dwarf galaxy", they are not synonymous.
"A supermassive black hole has been found at the center of a tiny galaxy, a rare find. What makes the discovery even more unique is that it has been located in an ultracompact dwarf galaxy, stunning researchers."
Yes, they really botched it, didn’t they? And how did the editor miss it. Perhaps he/she has absolutely no interest in the subject and so ran through it very quickly.
“UCDs are especially rare, as they are larger, brighter and more massive than other galaxies, including our own Milky Way.
What makes the find of the supermassive black hole at the center of the UCD so notable is that UCDs tend to be very small, with radiuses not exceeding 300 light years”
“contradicts”
Large vs small.
The small part is the radius. The large is the mass and volume. Why? because it’s compact.
E.g. a 5x5 square has an area of 25 sq ft and a perimeter of 20.
Take the same perimeter but squash it to a 9x1 rectangle and you’re down to 9 sq ft.
The square has a larger area because it’s more “compact”.
They should have denser.
UCDs are especially rare, as they are larger, brighter and more massive than other galaxies, including our own Milky Way.
What makes the find of the supermassive black hole at the center of the UCD so notable is that UCDs tend to be very small, with radiuses not exceeding 300 light years and an overall mass of several tens of millions of solar masses.
Editing might not have caught it; it was so blatant.