I'm not sure about the first post, but the second and third posts are not AI generated; there are some local Nigerian phrases and native food names ( e.g Ugu) that AI cannot pick up on, and the 3rd post AI does not write English that way, that's purely human.
If you ask any chatbot about popular Nigerian dishes it will come up with plenty of obscure things that only people from that region would understand.
The third post does not seem human at all to me. They have edited the post to make it look more human but it seems obvious that this was generated by AI. The language they use is very detailed but it is way over the top. Nobody in their right mind is writing forum posts about how they were hypnotized by a casino game and how it was whispering in their ear. Either this person is delusional or it is a completely fabricated story written with the help of AI.