Why is "Mourning of Muharram" trending?

Wikipedia Overview

Mourning of Al-Muharram is a set of religious rituals observed by Shia Muslims during the month of Al-Muharram, the first month of the Islamic calendar. These annual rituals commemorate the death of Husayn ibn Ali, grandson of the Islamic prophet Muhammad and the third Shia imam. Husayn and his small retinue were slaughtered in the Battle of Karbala on 10 Al-Muharram 61 AH against the army of the Umayyad caliph Yazid I. The battle followed Husayn's refusal to pledge his allegiance to Yazid, who is often portrayed by Muslim historians as impious and immoral. In Shia Islam, Karbala symbolizes the eternal struggle between good and evil, the pinnacle of self-sacrifice, and the ultimate sabotage of Muhammad's prophetic mission. Historically, the event served to crystallize the Shia community into a distinct sect and remains an integral part of their religious identity to date.