I think the root or the trans epidemic is actually adult men who want to invade women's spaces.
Sure, boys who like pink are deeply unhappy being forced into gender stereotypes, as are girls who want to play with cars, but those children don't have any economic power.
No doubt there have always been tomboys who told their parents they wanted to be boys.
Children wanting to be the other sex has been ignored while patriarchy was firmly established and it would have disadvantaged men to let women decide they were male.
Now that most explicit male privilege has been removed (except for some remnants like women being forced to wear high heels for some jobs, et cetera) and employers have been forced to pretend they pay women the same as men, restaurants cannot refuse to serve single women anymore, et cetera, it is more profitable for patriarchy to pretend that you can change gender. Men will still rape women who identify as male, will still discriminate against them, talk over them, mansplain to them, et cetera. As long as they can tell someone is actually female, they will mistreat her, but no one will have the language to talk about this, because there will be no statistics about the sex of perpetrators and victims.
Patriarchy, right now, does not lose anything by pretending that men see women who identify as male as men. (Even though that is obviously not the case)
It invisibles all oppression and gives men access to women's spaces, thereby increasing the rate of rape and other sexual assault.
There's probably not a secret patriarchy council that decided that the time is ripe - just many men who realized that, while previously, having their gender legally changed to female would mean other men are forced to oppress them in terms of wages, access to club memberships, et cetera, this is not the case anymore. Men still can oppress women, but since they can very well tell the difference, they still give transwomen male privilege, and still force female gender (i.e. oppression) on transmen. Many transwomen do not surgically transition, ensuring that no one will mistake them for actual women and discriminate against them.