I wouldn’t say the end of the Cold War ushered that in. McCarthyism, civil rights, Vietnam....we had plenty of infighting happening during the Cold War...Likewise off topic (somewhat)
Its interesting to note that the end of the Cold War ushered in Americans fighting amongst themselves. Slowly at first but gathered steam as the years passed by.
With no external threat we’ve fallen upon ourselves. I’m of the opinion there is no going back and is going to get worse, much worse.