No matter how good an AI ChatGPT is, all of its performance comes at a cost, and that is finite computation resources. Although OpenAI has bought and rented a lot of servers to provide its AI with sufficient power, there is still a limit. In rush hours, sometimes too many users use GPT, and it fails to keep up with them. So, it serves the maximum number of people it can at one time and leaves the rest to wait; those waiting will get “at capacity” notice. If a similar situation happens to you, don’t worry; nothing is wrong with the bot. It’s just too busy right now; you can try again after a few minutes or half an hour.