The linked article gives a reasonable possibility: Jody Herman, the paper’s lead author, told Spectrum News there are several reasons for the jump in the you

The linked article gives a reasonable possibility: Jody Herman, the paper’s lead author, told Spectrum News there are several reasons for the jump in the youth transgender population estimate, including that the CDC’s Youth Risk Behavior Survey began asking high school students in 2017 if they are transgender, giving researchers a clearer picture. Herman, a senior scholar of public policy, said other factors likely include shifting populations, greater awareness and education about trans people and gender identities, and increased social media that allows young people to connect with people they relate to. “I think it's a combination of things,” she said. “And we should be suspect of pointing at one thing.”