

Assuming you are in the US, you can sue over anything you want to. But there is a cost to that, and your management company may be banking on that cost being higher than your rent.
Also, if you have all the documents, you should be able to read those and learn what stipulations there are if the lease terminates and you are a month-to-month situation. It could be that you needed to give them more notice. They could have buried it in the fine print. It would suck to pay a lawyer money only to be told “yup, they can do it”, and now you are out more money.
You are now an American citizen, so you should have the rights the rest of us have. You should be fine. They haven’t gotten around to threatening to denaturalize people yet. When they do, they will concentrate first on people from countries they don’t like, that used old policies they have since rescinded. And they will have to use more due process than they are using on these non-citizens.
The one thing I would be cautious of, though, is the state of your cell phone. They are very thin-skinned when it comes to criticism lately, and may decide to look through your phone’s social media to decide if you are insufficiently loyal. They have broad powers to do that when you re-enter the country. As a US citizen they cannot deny you entry, but they can still make your life difficult on entry. And this group doesn’t exactly pay attention to laws, do they?
At minimum, you might want to shut down your cell phone before getting off the plane. Explain it by saying it is a long flight, and you wanted to save your battery for arrival. If they confiscate a phone and try to dump all its data, they are more limited if the phone has just rebooted. They would basically need the PIN to do anything. If you want to go further, you can also log out of all of your social media accounts and remove their apps before the flight, so they even if they force you to divulge the PIN they won’t find your social media history.
That may all be too paranoid, but we live in stupid times.