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.

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.