Computer generated?
Generated, I don't believe so.
Altered? Very possible.
Stangely, I've been kinda looking at this field lately from a serious-level observational standpoint (Yes, I know that this joke writes itself, but no, seriously, I've been studying the tips and hints of artificially generated images lately).
There are many aspects of this photo that make you believe that it was original. 1st, AI sucks at hands / fingers. I don't know why yet, but about 30% of all completely AI generated images usually end up with extra / missing fingers. 2nd, computers are still not great at shadows. If you look at her right upper forearm where she is leaning against the fence, you can see the proper shading of her skin (as two items get closer together, the shadow increases). That is tough for a computer to do, at least, not until you get up to the film-industry level of generated images. 3rd, the wispiness of some of her hair is photo-realistic, better than an AI image can usually pull off. 4th, the focus of her left elbow and the softness of the transition between her skin and the background seems to be shown correctly. So, at the least, I believe this photo has a real photograph base. If it's AI generated, its much better than average.
Now, with that said, there are also a couple of areas where I belive this photo has been "touched up". 1) Pretty sure the nipples were "enhanced". Look at the pattern of the top she is wearing. If you look a little under and to the right of her right armpit, you can see how the weave pattern distorts a bit due to the curvature of the breast. This makes sense, the fabric is getting pulled a little at that location. When you move to the nipple though, an area where you would expect to have a distinct distortion point due to a rapid change in surface area, the pattern remains perfectly square. 2) Her face has likely been touched up. She has a freckle or two on her arm, but her face doesn't have a single blemish. Also, the lighting is also a bit off and the skin tone of her face does not match her arms (her face is much lighter than her hands).