Is the yellow color found on underwear after waking up from sleep, which was not accompanied by a wet dream or a sensation of something being discharged, considered semen necessitating ghusl?

If a sleeping person wakes up and finds seminal fluid (maniy) on their garment, they must perform ghusl (definition) (ritual bath) even if they do not recall having a wet dream. If they are unsure of the fluid's nature, they have a choice: either consider it maniy, perform ghusl, and repeat past prayers; or not consider it maniy, in which case their prayer is valid if they purify the area of impurity and pray with a clean garment. This is the detailed view of the Shafi'i school, and it is the authoritative opinion (mufta bihi). In the case of praying with impurity due to ignorance or forgetfulness, repetition is not required, according to the more preponderant view (rajih (definition)).