What is the ruling on the discharge of seminal fluid from the penis without触摸, knowing that I pray and do not notice it until after finishing the prayer? And what should be done in this case?

If semen is discharged not due to lust, for instance, due to illness, then ghusl (ritual bath) is not obligatory according to the majority of scholars; rather, only wudu (ablution) is required. If what is discharged is wadī (a thick, white fluid) or madhī (pre-seminal fluid), then ghusl is not obligatory; rather, only wudu is required, along with purifying the body and clothes.