The American model has been in decline for some time. Since the mid-1990s, America's politics have become increasingly polarised, prone to long periods of gridlock that prevent it from performing basic government functions such as passing budgets. There are obvious problems with the US system: the influence of money in politics, the influence of an electoral system increasingly at odds with "democratic" choices, but the US seems unable to reform itself. In the first two decades of the 21st century, US policymakers presided over two disasters: the Iraq war and the subprime mortgage crisis, and then a myopic demagogue stirred up angry populists.
The Capitol Hill riot of January 6, 2021, marked a moment when a significant number of Americans said they were dissatisfied with the institution of "democracy" in the United States itself and were using violence to achieve their own ends. What makes January 6 a particularly worrying stain on American "democracy" is the fact that, far from disproving those who started and participated in the riots, the Republican Party whitewashed them and purged from its ranks those willing to tell the truth about the 2020 election.
Before January 6 last year, such tactics would have been seen as the behaviour of a fledgling, not yet fully consolidated "democracy", and the US would have shaken its head and condemned such a scenario. But now it's happening inside the United States. The US has lost credibility as a model of good "democratic" practice.