“oh yeah JKR is so MEAN to trans people cos she said only women have periods”
I don't think teens get as far as giving that as a reason even! Most of them I come across just take it as a given that she hates trans people and is unfair to them and says all kinds of awful stuff about them. They don't read any of it, apart from maybe some article from Glamour or something that supposedly explains how she is a transphobe, and only then if people seem clueless. Otherwise it's just taken as a total fact.
I wonder if part of the problem is that those who are GC tend to be older and less involved in social media. There is just so much - hundreds of facebook pages, let alone all the insta stuff, with cartoons, posts, memes etc that are so easy to read and share. Lots of manga characters and other teen friendly things, and it just gets repeatedly shared. Sometimes the pages share decent content about other topics, to draw people in, and then meanwhile fill their heads with trans-memes that are inaccurate (a bit like Britain First did - occasional decent points, and then pages full of racist rubbish once people liked their page). Creating manga illustrations, cartoons, memes etc seems to be a full time hobby for some of them, and then they get shared so much by supporters, or even people who just want to seem non-bigoted - and of course facebook's algorithms then direct even more of the same content their way. I've seen loads of it, despite never knowingly clicking on it - mostly because I think others on my feed may be subscribers. There are lots who like Harry Potter stuff, so they also easily get sucked into the trans stuff as a result, again by the algorithms, and they just believe what these endless cartoons and posts are telling them.
In contrast, I've never seen GC memes, cartoons, etc in the same way, only well-written and researched articles that nobody would really share as a quick thing on social media. And not with manga characters!!
We need more teens on this.