Absolutely this is the case. Out of curiosity I took a stab at creating some AI art recently. There are online services like MidJourney where you enter a prompt, i.e. a description of what you want, and a minute or two later it spits out some attempts. You get so many free and then you have to pay to keep using the service. Certain words in the prompt are forbidden, things like "nude" and "bare" to prevent people using it to make out and out porn. But you can also download AI creation software and run it locally. For that you download "models". Models being a specific term in machine learning / AI for something trained on a set of data - in this case images. A model is essentially a learned skill / behaviour / process. Some models are trained on sets of landscape images and buildings, others on photographs of real people, others on anime art. Roughly speaking, anyway. Different models are better or worse at certain things, some are very specialised, some are much more general purpose.
You can also mix and match models and train them yourself on images you select. This is where all my rambling about how it's done turns into a point. I went on a website looking through the different models available. This is normal, it's not suspicious or bad. You do this if you want to find models that are good for portraits, or sci-fi backgrounds or whatever. But in amongst all that there were more than a handful of example images for models that showed very young looking girls, usually in the anime style but occasionally photorealistic. It's fairly easy to mix and match models and blend what you want. You can produce adult nudes. I see no particular reason it would be difficult for someone to produce child nudes. And there are pornographic models you can add to other models. Well, technically speaking their a kind of modifying model called a Lora or similar types though Loras are the most popular I think. There are Loras that make the person in your image look like a particular celebrity, there are Loras that add penises or whatehaveyou.
People can share models between themselves - it doesn't have to be via a particular site. The software to run the models is already out there and it's generic with legitimate purposes.
I don't know of a way you can stop people producing images that are child porn without locking down everybody's computer and giving the police at will access to people's computers online and running some kind of 24/7 monitoring on my computer, your computer, everybody's. And there's never been a government in history I'd trust with that sort of power.
What I'm saying is we can still act on tips, reasonable suspicions or tracking people trading produced material with each other just as we do now. But there isn't a viable way to stop or reign in the technology. We are now at the point that you can take generalised AI software, tell it to produce a specific type of image and it will. And the software is open source. If you write something in it that says "don't produce a picture of a naked child" the person using it can just remote that limitation of the software by removing that bit of code.