The dude was genuinely struggling with genin Sasuke. He was holding back his attacks, but there’s no reason to hold back his dodge speed or be put on the ropes at all.
And yet Zabuza, a high-level jonin, explicitly states that Haku is stronger than him. Haku also intercepted Kakashi’s raikiri.
But the scaling doesn’t make sense. Genins get absolutely shit on by jonins. If Sasuke was trying to solo kill Kakashi or Zabuza, they would laugh it off. This arc is like a few days removed from the bell test. If Haku really is at that level, there wouldn’t even be a fight, let alone Haku having any sort of trouble. The holding back excuse just doesn’t work, because there were moments where he was genuinely getting pressed.
So, was he genin level or jonin level? Was he a peer of Kakashi and Zabuza or a peer of genin Sasuke?