It probably does some basic checks for adversarial text like putting AAAAAAAAA*, BBBBBBBBBBBBB*, [[[[[[[[*, or profanity profanity profanity then preprocesses the text before inputting.

EDIT: Only mentioning since some folks will argue chatGPT has a long crazy memory (10K tokens) because you sandwich stuff around some trivial 9.5k tokens of repetitions. They likely added a bunch of defenses against different basic prompt engineering attacks so people dont get it to say certain things too.