Must I repeat my prayers that I performed after seeing yellow discharge following a dream in which I saw something that aroused me, knowing that I cannot distinguish a woman's semen, and is this discharge considered semen that necessitates ghusl?

It appears that what you find after waking up is semen (mani), and it is not necessary for it to possess all the characteristics mentioned; some of them are sufficient. Shafi'i jurists have held that whoever doubts about a discharge can choose between the

things they are in doubt about. Some scholars have held that whoever omits a condition or a pillar out of ignorance is not required to repeat [the act of worship]. However, many scholars have held that ghusl (ritual bath) is obligatory if there is a

possibility that the discharge is semen. According to this view, ghusl was obligatory for you upon the first wet dream. If you did not perform it, then your prayers before ghusl were not valid, and you are required to repeat them. Repeating them is safer for

one's faith. As for seeking forgiveness (istighfar) and repentance (tawbah), a Muslim should always adhere to seeking forgiveness at all times due to the virtues proven for it. What you have mentioned does not attribute any fault to you except for

your negligence in learning the rulings of your worship.