I don't know why this is, but I read it here and found it to be the truth: Carbonation in the keg takes about a week to really get right, even if the gauge says it is at the correct level before that.
What I've been doing is spending about the first 48 hours at 30psi, then turn turn the gas all the way off for a few hours to see where it stabilizes... usually at that time it is around my target of ~12psi, maybe a little under. Physics would tell me it is properly carbed at that point. Then I bump the gas back on just enough to make sure it stays there.
The first time I was way impatient at tapped it at two days... not nearly ready.
At four days it is a lot better, but like I said it doesn't seem to be "right" for at least a week. I don't know why, but I agree it is better if you can wait at least that long. I haven't done a NEIPA yet, but most of my beers are hoppy ales with late additions and dry hops.