Davido officially welcomes new producer mr eff to his label
I'm not aware of any information about Davido officially welcoming a new producer named Mr. Eff to his label. Davido's record label is called Davido Music Worldwide (DMW), and while he has worked with many producers over the years, I don't have any information about a specific producer named Mr. Eff joining the label.
It's possible that you may have come across a false or outdated report, or that Mr. Eff is a new producer who has not been officially announced by Davido or DMW. If you could provide more context or a source for the information, I may be able to help you further.