Why does Graphrag tend to weave information rather than use the indexed data directly?

[MinzhiHuang]

I input over 1000 articles and indexed them. I queried information about one specific entity (for example, Joe Biden) and want to retrieve all the relevant information. But rather than giving the information that indexed, the LLM made up some articles information and give it to me. Just wondering why? Is that due to the way I query? Query: "find all the articles which relatives to XXX and list then all with their source." Model Qianwen.