The theme for 2023 has yet to be posted (September 2022)
International Day of Remembrance of the Victims of Slavery and the Transatlantic Slave Trade
The UN “Outreach Programme on the Transatlantic Slave Trade and Slavery was established in 2007 with the adoption 
of the General Assembly resolution 62/122. The Programme raises awareness of the history of the transatlantic slave trade, its impact on the modern world, and its legacies, including racism and prejudice. Over the years, the Programme has established a global network of partners, including from educational institutions and civil society, and developed resources and initiatives to educate the public about this dark chapter of history and promote action against racism.”
UN Outreach Programme on the Transatlantic Slave Trade and Slavery
There are two days of Remembrance on this topic: one in March and one in August.