Well it's primarily driven by what's going on in China, not what's going on the US. The prior three decades were driven by the line of thought that a prosperous economy tends towards democracy and that prosperity prevents war. Allied to this, the expectation was that this would be mutually beneficial with both parties pursuing it in good faith.

Since then, it's become clear it's not the case. China have found the loopholes, their lack of IP enforcement and government corporate espionage have shown the relationship is asymmetric and to the detriment of the US.

Xi has also strengthened his hold on power dramatically, breaking with his predecessors gradual loosening of control. This leads to more risk of irrational ideological driven decisions such as war, maintaining prosperity is no longer necessarily the main driving factor.

Intelligence around Chinese military build up around Taiwan are concerning evidence of this. The Chinese economy's rapid growth is also slowing.