Childhood depression was definitely overlooked in previous generations.
There’s pretty much no data from the 21st century. Almost everything on the topic only goes back ~20 years. That suggests no one gave a fuck.
There’s been a trend in improved diagnostics and more serious research on childhood depression in recent years, which can explain some of the rising rates of childhood depression (they’re not just in the US).
But there might also be a real rise in depression. The pandemic affected everyone, so that’s an obvious causal factor for some of the years. There’s also social media and the rise of “influencers” and all sorts of things that can affect self-esteem and create unrealistic expectations.
We can be sure that it has nothing to do with children being told they’re a different gender in schools, or any other evidence-free right-wing bugbears.