Well, the black hole isnt hydrogen. This is the gas around it. And being pure hydrogen seems sus as there should be some helium in there according to most models.
Not only that, but getting stars to form using pure hydrogen is tricky. That helium helped early stars collapse and ignite. Not seeing any helium in an early-universe object is a big deal, suggesting some sort of error.
https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis
Not only that, but getting stars to form using pure hydrogen is tricky. That helium helped early stars collapse and ignite. Not seeing any helium in an early-universe object is a big deal, suggesting some sort of error.