To the best of my knowledge, there is no purpose or plan to intentionally leave human poop on the moon. there have been several moon missions conducted by various countries, including the United States, Russia, and China, but none of them have involved deliberately leaving human waste behind.
The primary focus of lunar missions has been scientific exploration, gathering data about the moon's geology, conducting experiments, and studying its environment. The missions have involved deploying rovers, collecting rock samples, studying lunar soil, mapping the moon's surface, and conducting various other experiments.
While waste management and human sustainability in space are important considerations for long-duration space missions, such as those aimed at Mars exploration, the current protocols and plans involve recycling and minimizing waste. For instance, on the International Space Station (ISS), waste is carefully managed, treated, and recycled to maximize efficiency and minimize the impact on the environment.
However, as of that time, there was no known purpose or intention to leave human poop on the moon during any planned or conducted missions.