Is the prayer valid if I perform ablution and pray before the prayer time expires, then the time expires during the prayer, based on the view that yellowish and brownish discharges are not menses, and nothing was discharged after the prayer? Does the same ruling apply to ablution for Qiyam al-Layl or Duha prayer if the time for 'Isha or Fajr expires after the ablution?

The summary of the fatwa (definition) is that the excused person, such as one with urinary incontinence (sals) or continuous yellowish discharge (sufra), does not have their ablution invalidated by the entry of a new prayer time if nothing has exited from them. Their purity (tahara) remains valid and intact, whether it be upon the entry of Duha time or any other time. It should be noted that the time for Isha extends until Fajr, and after one-third or half of the night, it becomes a time of necessity. The Maliki school of thought holds that the purity of a person with sals is not invalidated by the passage of time at all, and this is a strong opinion that can be adopted when needed.