One thing I haven't heard much discussion about is the fact that ChatGPT is constantly being updated.
This means that if you build a prompt for classification and become confident that you've whacked all of the moles so that it is pretty solid with all of the edge cases, it can later start breaking again.
Some solutions I can think of are 1) choose a fixed model to test against but they become deprecated over time or 2) perhaps fine-tuning might help.