Here's the challenge. With a single PoD, as close to the present day as possible, have at least a single major country/a significant part of the world, have legal actual chattel slavery. To clarify, chattel slavery means that individuals are reduced to the status of private property and can be owned by people, so just having forced labour doesn't count, so indentured labour and Gulags don't count. Also you can't just have the Nazis win and then decide to bring back slavery. Whilst I don't doubt that they would have been up for it, it's just too easy. Same goes for having Daesh/ISIS miraculously win.