How does a menstruating woman know that she has had a wet dream, necessitating ghusl (ritual bath), given the impossibility of seeing semen due to the presence of menstrual blood? Does she rely on feeling pleasure in the dream? And does the ruling differ during menstruation compared to other days?

A woman is not required to perform ghusl (ritual bath) due to a wet dream unless she sees the semen that necessitates ghusl. If she does not see semen on her body or clothes, then ghusl is not obligatory for her. The statement that menstruation prevents the discharge of semen is not accepted. And even if that were assumed, her ghusl for menstruation would suffice for ghusl from janabah (ritual impurity requiring ghusl) according to many scholars.