GPT3 / ChatGPT may seem smart from the outside, but it is simply a large language model learning patterns in data. Using something like this for figuring out disinformation would be a rather bad idea because of all the biases it would introduce. You instead want a model specifically for the task of misinformation with the biases reduced as much as possible, and there are already thousands of research papers on this out there -- its a really hard machine learning problem.