The holiday was originally created by the Ayatollah Khomeini in 1979, when he announced:
I invite Muslims all over the globe to consecrate the last Friday of the holy month of Ramadan as Al-Quds Day and to proclaim the international solidarity of Muslims in support of the legitimate rights of the Muslim people of Palestine. ... I ask all the Muslims of the world and the Muslim governments to join together to sever the hand of this usurper and its supporters. I call on all the Muslims of the world to select as Al-Quds Day the last Friday in the holy month of Ramadan—which is itself a determining period and can also be the determiner of the Palestinian people's fate—and through a ceremony demonstrating the solidarity of Muslims world-wide, announce their support for the legitimate rights of the Muslim people. I ask God Almighty for the victory of the Muslims over the infidels.
I always though Jews were dhimmis,. not infidels (kafirs) - but who am I to argue with the Ayatollah?
Quds Day is held on the last Friday in Ramadan, which would have been May 7 this year.
Iran is now seeing record numbers of deaths and illnesses from COVID-19.
But not to despair - the festivities might still occur in London, which has an enthusiastic Quds Day rally every year.