What is the ruling on the prayers I performed while wearing water-resistant eyebrow kohl? Must I repeat them, given my previous ignorance, and what if I die before completing the re-performance?

If kohl prevents water from reaching the skin, then ablution (wudu') performed with it is invalid, and consequently, the prayer is invalid.

The majority of scholars believe it is obligatory to repeat prayers that were performed with an invalid ablution due to ignorance. Ignorance removes sin but does not waive the obligation (of performing the act correctly). The view of repeating the prayers is more cautious.

However, Shaykh al-Islam Ibn Taymiyyah and those who agreed with him held that an ignorant person is excused and is not required to repeat acts of worship that were invalidated due to their ignorance. This view has strong merit, and there is no harm for someone who adopts it.

According to the view of making up (qada'), the method of making up should be according to one's capacity and in a way that does not harm the body or livelihood. If death occurs before the make-up is completed, there is no sin.