There are actual cats that look like this, so probably it's real. It certainly doesn't seem AI generated to me.
GPTs also don't make images. That's not what Transformers do, and GPT means Generative Pre-trained Transformer. It's diffusion models and variational autoencoders that make images.
To me it looks like they used a bad camera that's too soft. That's all. AI images are often sharper and better looking than this if done using a good enough model and techniques.