Fair enough, but how about physical communities with no selection bias? In 2017 10% of California high schoolers identified as LGBTQ, in 2021 the number was 15%. These numbers vary heavily based on how leftist the community they live in is -- that 15% number is for California in aggregate, including extremely conservative parts of it. (Remember about a third of California is conservative -- there are a hell of a lot of people in California who don't live on the coast). In heavily left-leaning areas, there are high schools where 25% of the students self-report as LGBTQ.
These are largely people going to school where they were born -- high schoolers don't usually move to another state to be with people like them like older people do.
I posit that the change is because, for people who feel marginalized socially, it's gone from being accepted as an equal if you're queer, to feeling left out if you're not.
I will die on the hill that this is exactly what happened to Chris, only much later in life -- but on a maturity level, high school students are wizened elders compared to Chris.