Many times, when I read African fantasy, there is always something that feels off, something that is not exactly smooth when compared to western fantasy.
It took me a while but after I read "black leopard, red wolf" by Marlon James and compared it to "The name of the wind" by Patrick rothfuss, I realised that to write African fantasy is beyond just changing up the names, settings and culture.
Western fantasy is grounded in a lot of folktales and mythologies, tropes and patterns of storytelling (mostly linear). It is usually "this happens, this happens and this happens," most African folktales do not go that way. There are, sometimes, jagged storytelling, circular storytelling and the prose choice is mostly different, riddled with mystery and awe, adages and proverbs (which adds an interesting flavour to the prose)
It is more than the setting. In my opinion, if you want to write African fantasy then you have to actually write it true and naked, uninfluenced by Western storytelling. (All of this is in my opinion).