It's nothing. It's completely outside the criminal justice system. It's not even a misdemeanor.

Without a current visa of some kind though, you are deportable, mostly at the whims and mercy of the government. But you wouldn't be committing a crime and deportation is not a criminal punishment.

When you do crimes, you get criminally punished (hypothetically) citizen or not (jail, fines, etc).

Whether the government can, should or must carry out a deportation are all truly separate considerations, often with distinct, case-by-case answers.

And with all this in mind, pause for a moment and sit with the fact that thousands of people who have committed no crime at all are getting grabbed off the street and incarcerated indefinitely by ICE and subjected to ghastly conditions

It's a civil infraction, like a speeding ticket or a heavy equipment rebuilder that makes the mistake of painting a bunch of stuff with paint that doesn't meat whatever this years EPA VOC rules are.

If you're not rich enough to lawyer up, spend five figures fighting through the kangaroo administrative process and then another five sticking it to them in real court a civil infraction is actually worse in a lot of ways because those pesky 4th through 8th amendments don't really protect you all that much. There's a lot of judicial precedent from the past 100yr that basically waters down your rights when a bureaucrat is after you rather than the cops.