There have been several coups or other undemocratic assumptions of power recently: Saudi Arabia, Lebanon, China (Xi seems to have made himself dictator-for-life), Turkey, and to a degree in Japan, in at least one Eastern European country, and even in France (which AFAIK now has an indefinite state of emergency curtailing rights of citizens). I wonder how much and in what way they are related to the U.S. changing its…
Saudi Arabia and China have not had coups, and are not democratic countries, so any change is "undemocratic", but that's not a chance and means little. Xi's actions are hardly different that Deng's or, before him, Mao's. Lumping them in with Turkey, which is experiencing a slow motion coup, is bizarre.
Conversely, Japan and France have neither had coups nor an "undemocratic assumption of power", so clearly don't belong in the same list as Turkey. Lebanon I'm not really familiar with, and I don't even know what Eastern European country you're talking about, so I can't comment on them, but the rest of your list makes no sense. Nor does Zimbabwe fit on your list; the coup is a best neutral in terms of democracy, and could be a step towards greater democracy.
> I wonder how much and in what way they are related to the U.S. changing its long-standing policy from being the guarantor of international order, and from being an advocate for democracy as a universal right
Unless you're talking about the second President Bush's much maligned (and mostly unsuccessful) foreign policy, I have no idea what you're talking about. The US has not traditionally advocated for democracy as a universal right, and it spent much of the Cold War backing dictators and, in some cases, overthrowing elected governments.
> That trend, away from democracy,
By which you mean "Turkey"? (And maybe Lebanon; again I'm unfamiliar with the situation there.) I see no trend.