From your link: "sent in error"
I have no idea what that means.
I'm not making the claim but feel free to provide plenty more.
Nah, I think you're being obtuse on purpose, so I'm going to let you do your own research.
Which country would they self deport to if they were born in the US?
Again, seriously? That's what you take from this? US citizens are being told (threatened) to leave the country within 7 days, or else? You don't think that's way over the top? Some even felt so threatened that they hired a lawyer.
Two more examples.
A man who was born in Georgia was detained by ICE in Florida, probably because he had a Latino name, or because he looked Latino. His mother came down to show the judge his social security card and birth certificate, and still they wouldn't let him go.
https://www.nbcnews.com/news/latino/us-born-citizen-detained-ice-immigration-florida-rcna201800
ICE agents smashed the car window of the wrong guy, while his wife and young child were in the car.
https://www.youtube.com/watch?v=rJ5YZQtJz7Y
The point is that ICE is overstepping its legal authority by miles and miles, and that ICE agents act like goons and thugs, because they know there will be no repercussions. As you can see in this thread, many don't give a toss about the constitutional rights of anyone they don't like, and they actually even approve of it when these rights are very obviously violated.