It's extremely complicated. Actual CSAM is very illegal, and for good reason. However, artistic depictions of such are... protected 1st Amendment expression[0]. So there's an argument - and I really hate that I'm even saying this - that AI generated CSAM is not prosecutable, as if the law works on SCP-096 rules or something. Furthermore, that's just a subset of all revenge porn, itself a subset of nonconsensual porn. In the US, there's no specific law banning this behavior unless children are involved. The EU doesn't have one either. A specific law targeted at nonconsensual porn is drastically needed, but people keep failing to draft one that isn't either a generalized censorship device or a damp squib.
You can cobble together other laws to target specific behavior - for example, there was a wave of women in the US copyrighting their nudes so they could file DMCA 512 takedown requests at Facebook. But that's got problems - first off, you have to put your nudes in the Library of Congress, which is an own goal; and it only works for revenge porn that the (adult) victim originally made, not all nonconsensual porn. I imagine EU GDPR might be usable for getting nonconsensual porn removed from online platforms, but I haven't seen this tried yet.
I'm disgusted, but not surprised, that teenage kids are generating CSAM like this. Even before we had diffusion models, we had GANs and deepfakes, which were almost immediately used for generating shittons of nonconsensual porn[1].
[0] https://en.wikipedia.org/wiki/Ashcroft_v._Free_Speech_Coalit... and the later https://en.wikipedia.org/wiki/United_States_v._Handley