I assume you’ve heard of affirmative action. I don’t know if they have it in Switzerland. I’ve worked at multi-national companies and in my performance plan under Diversity, it said I must “hire, develop and promote minority and women employees”. If I did not have diversity on my team and a list of diverse talent I was developing, it was my job at stake. I’m not saying there isn’t a glass ceiling, but it is rather high and full of cracks. Granted, not enough companies do this, but there are some. I think our competitiveness was better because if it. The ones who do, let it be known.
I’m not going to give you any advice because I know exactly who you are talking about. I’ve seen them too. Generally, advice should be requested, not offered, regardless of skin color or gender.
But, I will say that a lot of black women don’t really agree that it is as bad as you say. They seem to be successful and, though under-represented, it isn’t a small number. I hope you can find better mentors who have shared your experience and don't feel they need race quotas to succeed. If you don’t know any, I can introduce you.