I'm honestly a little surprised it didn't start before then. With the 2008 "Great Recession" I remember quite a few people and teenagers struggling back in my high school. I knew a lot of teens/families who lost their homes, or had to get jobs to support their families etc and drop out of school. I remember that having a big impact in my life, so I get I would have expected that to have had a greater influence.
At least with measurable indicators of mental health crises like suicide rates, groups that are worst off by most socioeconomic measures tend to have lower suicide rates. For example, the black suicide rate in the US is less than half the white suicide rate and have been through Jim Crow laws and generally much lower SES. From what I've seen, the same is true when comparing across countries, with suicide rates being positively correlated with GDP and income.