Because with age gaps starting that young (and 19 is legal, but it's still young), this is often the form that power imbalance takes.
It's easy to have this conversation online devoid of nuance and subtlety (as is the online way). In that way, people tend to think of power imbalance as an obvious thing that people willingly and knowingly abuse. But that's often not the case.
In reality, power imbalance can be as subtle as the fresh adult enamored by the older person giving them the time of day, and the older person infatuated by the doe eyed youth who isn't experienced enough yet to see their flaws (which we all have).
Granted, the term "red flag" does is not a definite. It's by definition pointing out warning signs, which is all I'm doing. OP is grown, and so is that 19 year old. But they also created this thread asking for advice from strangers on this internet. And there are red flags. I would ask OP to consider why this 19 year old who seems mature for their age also makes them feel wanted. Ultimately, they're going to do what they want, but they should keep that in mind.
