Hubert Reyk is a Higher Vampire
Late to the party, but I think about this quite a lot in my current playthrough and here’s what I think, or rather LIKE to believe:
What previous posters said about the retcon in B&W making things difficult is 100% correct and Projekt Red was a bit lazy, as they could’ve easily addressed the confusion with an optional prompt in any conversation with Regis.
But that doesn’t mean Hubert is not a Higher Vampire. Here’s why:
He knew he got caught red-handed and his cover was blown. So there was no going back to his old identity that had started to outgrow its use when former colleagues started to notice he was not aging. He had to change soon anyways, which may have prompted his killing spree as well. So what was Reyk to do? He knew Geralt would pursue him, he knew he couldn’t go back to his identity. So he changed into his Katakan form, gave Geralt a run for his money and “died”, knowing he could regenerate any time he liked and relocate.
The game also supports this, because we can still find his letters long after he was killed and the game retains him as the face of the “Higher Vampire” bestiary entry. Everything else is poor retcon by Project Red.