> If you want to posit an explanation for this phenomenon, you have to be able to explain two things: what changed abruptly in the early/mid 2010s?, and why did it uniquely affect teen girls?

And that it's cross-cultural, so three things.

> and yet it's much less clear now that there is any gender difference in technology uptake.

There are definitely well known differences in how the tech is used by the different sexes. Females are typically far more social than males.