It's something that is not easy to find information on due to the sensitive nature of the subject. But with just a bit of google, you can find things like this:

https://www.thelocal.fr/20160109/immigrants-struggling-to-in...

The article there seems to be saying even with 2nd generation immigrants from africa are reporting less integration as they feel more isolated from the identity than their parents and find themselves worse off economically.

So if this is the case, I don't see any reasons why the 3rd generation and onwards would suddenly bounce back from their isolated and relatively poor positions on their own without more intervention from the host nation.

Combine that with new waves of immigration, why wouldn't you see some of these 3rd generation ethnic africans find new identity in the africans that have just showed up?