SCOTUS is pretty clear about fictional depictions of children, provided that such depictions are distinguishable from the real thing. So using AI to create virtual CP that looks exactly like real CP would still be illegal, but drawings that are obviously drawings aren't.

https://firstamendment.mtsu.edu/article/ashcroft-v-free-speech-coalition/

I only found two examples of prosecutions of virtual CP after this case, and one of them involved a guy who also possessed real CP. Regardless, surprise surprise, but crooked cops, DAs, judges, etc don't give a lick of a shit about the Constitution, and will simply disregard it knowing that most people don't have the resources to challenge them. Especially if they can get a plea deal that doesn't completely destroy their life, unlike spending several years in court which will only cement their reputation as a degenerate.