Frau Merkel is concerned about the laws being proposed by the government effectively to curb the power of the judiciary, but it is, in answer to the OP, actually the EU itself which has been the primary source of opposition to this, as the proposals flout EU rules about that. A lot of EU rules are there to guarantee freedoms not take them away. Of course, if a country democratically wants to do away with all that stuff, then it can do so, but cannot expect to go unpunished. It can even leave. But no one in Poland wants to leave the EU: not even the ruling party.