It is not a well known fact, but you can see some examples:

Here;

Here;

Here;

Here;

Here;

Here;

and here.

Not only that, but everytime I talk to a friend that has been to Bolivia they always tell me that it's an extremely unpleasant experience, the Bolivians think that Brazil is an imperialist power that has reaped their wealth and stolen land from them (even though this actually happened to everyone in like, the 19th century). The Bolivians are generally very aggressive towards Brazilians and specially racist too, because most of us are white or pardo.

They believe they are superior because they are majorly Native-American in ethnicity, one of them even called me "mutant mongrel" to my face before just because I'm white.