The Younger Dryas Impact Hypothesis is not quite confirmed, but is probably going to be generally accepted within the next few years. The most recent review I'm aware of is Sweatman's 2021 [1] article arguing that we're already there. He makes a very relevant callout in the paper as well:
The proposal is that this impact triggered the Younger Dryas (YD) cooling and contributed to the end-Pleistocene megafaunal extinctions and human cultural changes. Equally, it should be clear that Firestone et al. (2007) are not claiming that the impact event itself wiped out many genera of megafauna or an entire human culture in an instant.
Of course, it's pretty obvious that the late quaternary extinction events weren't solely related to any particular impact event, if for no other reason than that many of the extinctions pre-date the impact and we can see the decline in North American megafaunal populations long before it.
[1] https://doi.org/10.1016/j.earscirev.2021.103677