Online friend charged with making indecent photographs? (England)

My online gaming buddy of several years has suddenly vanished. Getting worried I did some digging and found a recent court case with his name and location matching. He was sentences to 2 years in prison. Please help me understand what did he actually do?

The charges are as follows:

"Possession of an extreme pornographic image involving sexual acts with an animal. Making and distributing indecent photographs or pseudo-photographs of a child (two counts)."

He writes fan fiction about fictional characters who are under aged and can turn into animals. A mutual friend was theorising that maybe he had an AI generate some furry porn essentially. Could it be it? I find it very confusing that a first time offender goes to actual prison for that. Surely it has to be worse, right? And if so, how bad is it?