The ChatGPT UI is indeed a wildcard. But it is irrelevant here because according to the github repo this page queries the API and OpenAI guarantees it doesn't c

The ChatGPT UI is indeed a wildcard. But it is irrelevant here because according to the github repo this page queries the API and OpenAI guarantees it doesn't change models with version number information (like gpt-4-0613, which is mentioned in the latest images). So this "experiment" would make a lot more sense if it was only run once every few months when the API actually offers new model versions and then generate a bunch of images for every model, instead of generating one single image every day (which is meaningless due to non-deterministic noise, even if the model had somehow changed since yesterday). That is also how it was done in the original study during the development of GPT4. I don't know how this experiment came up with its logic, unless they had a gross misunderstanding about how these models actually work (which admittedly seems common among tech interested folks here).