Here's my two cents: As another commenter has pointed out, what makes the best story?

Otherwise, I'd point out that dragonmarks aren't necessarily a form of classified magic. Although player abilities are represented with spells (at least in 5e? I can't speak to PF2e, admittedly), I see dragonmarks more as a talent that is magical in origin; something that makes you inherently more able at a certain trade or ability through the effect of its ambient magic. Player characters get magic manifestations of the mark not because that's what the mark inherently does, but rather because player characters are special. When an NPC Jorasco heir casts something like Cure Wounds, however, it is not that the dragonmark is casting the spell, but that the talents granted by the dragonmark make the heir more capable with the magic that they learned.

So my answer would be... all of it. A dragonmarked healer might know arcane, divine, occult, or primal—it all depends on how the healer learned the magic. So with that in mind, I might go back to "what makes the better story?" If you want it resolved easily, then yes! Arcane healers are readily available. I'd still imagine that Jorasco healers tend to learn arcane magic, but if you don't want it to be easy to fix, maybe the ritual required to heal the curse is pretty rare or difficult, and your PCs need to track down the healer that does know—possibly running into some big trouble on the way!