One factor might be the increase in binge drinking during the pandemic, which I suspect fuels at least a certain fraction of anger and bitterness, along with the post-alcohol depression effect, in conjunction with economic and related stresses:
> "Using data from a national survey of U.S. adults on their drinking habits that found that excessive drinking (such as binge drinking) increased by 21 percent during the COVID-19 pandemic..."
Even moderate drinking has significant lasting physiological effects like elevated heart rate as well as reduced sleep quality and emotional disquiet. It’s just if you drink regularly that all starts to feel normal.
I do drink by the way, although very infrequently. I judge that the pleasure I can get from a top shelf bourbon on rare occasions is worth the harm. But when you don’t drink regularly if you’re at all in tune with your body the effects are quite noticeable.
> "Using data from a national survey of U.S. adults on their drinking habits that found that excessive drinking (such as binge drinking) increased by 21 percent during the COVID-19 pandemic..."
https://news.harvard.edu/gazette/story/2022/01/covid-related...
Exercise and a healthy diet can benefit one's state of mind, in contrast.