Space

The researchers were also perplexed by the incredibly small sizes of these systems, only a few hundred light years across, roughly 1,000 times smaller than our own Milky Way. The stars are approximately as numerous as in our own Milky Way galaxy—with somewhere between 10 billion and 1 trillion stars—but contained within a volume 1,000 times smaller than the Milky Way.

That kinda self-explains why there's a supermassive black hole at the center of this young galaxy (all galaxies) right? As in the early universe was small and lumpy, with the first matter so close together, that it rapidly formed supermassive stars and black holes — maybe the density was so high that the first stars had no time to supernova and distribute higher elements; with billions of stars colliding into black holes over hundreds/thousands of years, each collision jumping the event horizon to insta-absorb thousands more stars at the speed of gravity/light — the first black holes going through a rapid period of exponential growth, getting to 50+% of their current size within a fraction of their entire existence.