Haidt brings up those points in the testimony to rule out other factors and prove that social media is specifically to blame.
Mental health as well is a moderately subjective matter, and there's no doubt that the self-reported aspect of mental health problems has been highly influenced by cultural and societal changes, like how the public perception of mental illness has changed over time. Likewise I'm sure men and women think differently about this, and I'm sure the societal expectations of men/women impact it as well. When we talk about mental health getting worse over time, or impacting women more, this is inherently imprecise.
But suicide is suicide: From 1981 to 2017 the male suicide rate per 100,000 in my country (the UK) has gone from 19.5 to 17.2. The female suicide rate has gone from 10.6 to 5.4. Mostly good news: the rate has gone down.
But the gap between men and women has increased, men have gone from roughly twice as likely to kill themselves to about three times as likely as women.
It's sad that even now concern about mental health only seems to get weight when phrased in a way that makes it sound like it's impacting women more, when one of the more concrete, key statistics clearly indicates it could be the other way around (and getting worse). This observation may very well be related to the disparity at this point.
2) seems to point the finger at social media more heavily though I think, but I'm not entirely sure what to make of that but this point is convincing to me.
The depression in the early 1990s was another story. It may have hit Finland worse than the Great Depression in the 1930s.
At college my social feeds where friends and clubs I picked, by university 3-4 years later, Facebook et. al was feeding me a lot more other stuff intermixed with friends posts.