What is the ruling on the emission of a small amount of clear and viscous fluid from the vagina immediately after prayer, when it is uncertain whether it was emitted before or after the prayer?

Everything that exits from the two private parts (front and back) invalidates ablution (wudu') and is impure (najis), except for semen and the moisture of a woman's private part, concerning which there is a difference of opinion, and the relied-upon (mufta bihi) opinion is that they are pure.

If someone purifies themselves and prays, then sees impurity on their garment after the prayer and did not know about it before, their prayer is valid, and they are not required to repeat it. Similarly, if they are not certain that this discharge occurred after ablution, their ablution is valid because certainty is not removed by doubt.