> It's just hard to wrap my head around what this trend would be, or why teens started picking up on it in 2012.
One reason could be they started talking to each other more. Women and girls who had similar life experience shared them on the internet. This is how the whole Me Too movement started; the experiences shared during the Me Too movement were old, but it was the internet and social media which acted as a catalyst to dislodge them from the past and bring them into the present.
> I am not conscious of any major modern debates around women's rights except abortion/birth control
Don't you recall the 2016 Presidential election? There was a huge debate about whether or not a woman was ready to be President of the United States. I don't know about your family, but in my family people thought it very clever to say that a woman could never become president, because her period would make her too volatile. This kind of rhetoric may have flowed right past you, but it wasn't lost on women (especially the very cogent point that men have in fact started most wars in all of human history).
The outcome of that election was that America chose a serial sexual predator who has admitted to spying on women in changing rooms, has raped women, and who has admitted to using his power and prestige to assault women. It wasn't lost on women that this man, with a famously volatile temper, was chosen over a women because he was viewed as more trustworthy and more stable than her.
That man ended his term by waging a violent coup against the United States government with his supporters, who themselves made an effort assassinate the vice president. Yet it was the female candidate that America considered a priori too "volatile".
> I thought only ~8% of women had abortions, but in looking it up while writing this comment apparently it's more like 25% (so abortion & related issues affect way more women/girls than I expected).
As with rape, the number of women who have abortions and the number of women who report abortions are quite different. That number is going to diverge even more now that it's illegal and criminalized in many jurisdictions.