Fareed Zakaria describes this in a recent video (it says "Western civilization" but the great majority of the focus is on the USA). TLDR: everything is different now than it was a year ago.

This short video does not really go into why, e.g. a change in the desires of oligarchs, probably fueled by climate change. A different video of his also covers some of the false narratives surrounding the topic. The last minute or two there (though it's only <6 minutes total, worth listening to it all to get the full context) helps explain some of what you are looking for: there is no one "America" (nor just one "China", or "France", etc.) - there are shared cultural values, which change over time.

"Citizenship" may be a piece of paper, but to be American is more than that. Though precisely what that means is currently changing (same as it ever was). It used loosely based upon a Judeo-Christian worldview (where atheism and agnosticism was still acceptable) and strongly valuing individual freedoms - to speak, to own a gun, to move from place to place, etc. Now it is quickly turning towards more Christian Nationalism (where "christianity" means whatever those currently in power want it to mean, in that moment), and along the spectrum of more states rights over those of the individual, e.g. cancelling the right to speak, recently we hear that gun ownership is in question, and as this continues the right to move will become more restrictive - e.g. as California and other "blue states" work to separate themselves from the rest of America, and "red states" also do the same, they may start imposing additional restrictions on where people are allowed to live.

Oh well, the only constant is change. What will be will be, so seize the day while you can regardless and as best you can!:-)