I've never seen a clear explanation of the right's grievances regarding Soros, but what I can put together contextually is that he is a wealthy source of finance or power brokerage for political action involving anything left of far-right. There is also a deep, non-explicit anti-semitic tinge to it all as well.

However everything I have heard him about his didn't come from credible sources. I've honestly wondered for a long time as well.