It's similar in the USA. Black Americans do poorly. Black Nigerian immigrants to great. They're both black so it's evidence race has little to do with whatever the problems of class are but a certain segment of vocal people ignore this evidence.
There is a literal mountain of evidence that both color and race in the US correlate negatively with outcomes, perhaps in differing amounts, but if you ignore that, you’re also ignoring some evidence. There a lot of possible confounding reasons why one black group might fare better than another on average in the US, and that means that if you care about being accurate about whether race and class are linked, then it’s extremely difficult to separate them, and nearly impossible to declare they’re not linked. The biggest problem with your claim is that race and class absolutely were linked in the past without question, when blacks were slaves, and we have never had a period in US history where the socioeconomic outcomes of blacks matched whites on average. The situation has improved, but we have plenty of evidence we’re not there yet, and so it’s impossible and almost certainly wrong to claim that either race or color has little to do with class.