The porn industry is, in fact, extremely hostile to AI image generation. How can anyone make money off porn if users simply create their own?

Also I wouldn't be surprised if the it's false advertising and in clicking the ad will in fact just take you to a webpage with more ads, and a link from there to more ads, and more ads, and so on until eventually users either give up (and hopefully click on an ad).

Whatever's going on, the ad is clearly a violation of instagram's advertising terms.

I’m just hoping I can communicate the danger of some of the social media platforms to my children well enough. That’s where the most damage is done with the kind of stuff.

It's just not your children you need to communicate it to. It's all the other children they interact with. For example I know a young girl (not even a teenager yet) who is being bullied on social media lately - the fact she doesn't use social media herself doesn't stop other people from saying nasty things about her in public (and who knows, maybe they're even sharing AI generated CSAM based on photos they've taken of her at school).