The title here is simply wrong, there's no nuance that could possibly make it correct. Nethack, by design, changes the gameplay (slightly for some characters,

The title here is simply wrong, there's no nuance that could possibly make it correct. Nethack, by design, changes the gameplay (slightly for some characters, greatly for others) based on the phase of the moon. It tells you this, the same way the game tells you everything else. There is no sane justification to call this a bug on either side, it's just a poorly trained model responding poorly to a feature it hadn't seen in training