Seems to be conflicting theories on this question. I decided this was a good topic for this week’s Weirdness Wednesdays post. I see a lot more articles in my search for Theory #1 when I looked than for Theory #2. Using your favorite or least favorite search engine, Your Mileage May Vary (YMMV).
Theory #1 (so named because it’s the first theory I came across a few days ago; it was a different article than this one, but this was the first to show up in today’s search – it makes a good point that wasn’t in the first article I found) – https://www.space.com/monster-black-hole-disovery-too-big-theories.html
The researchers do acknowledge some caveats with the study, according to Science News. For example, the mass of the black hole depends on its calculated distance. Europe’s Gaia space telescope, which precisely measures the movements of a billion stars, has suggested that the distance to this black hole might be only about 7,000 light-years, or roughly half the distance the Chinese team calculated. If that’s true, the black hole would be only 10 times the mass of the sun.
That said, the Chinese-led team noted that, if LB-1 were closer, it would be less luminous and less massive — and its observed temperature cannot be explained with less luminosity. Also, the discrepancy with Gaia’s data could be explained if the star were excessively wobbling around the black hole, Science News noted.
Other Weirdness Wednesdays posts: https://upsdownsfamilyhistory.wordpress.com/tag/Weirdness-Wednesdays/