Wind tunnel simulation result problem with the input of Butterfly Refinement Region

Hello, I am currently running a residential wind simulation with an open hole, but I have noticed that when the Butterfly_Create Case from Tunnel battery is connected to the Butterfly_Refinement Region battery, the results of the simulation change drastically, and the difference in the average wind speeds can be more than 0.1m/s as shown in the graph, sorry, but I am not sure what is the reason for the Butterfly_Refinement Region’s influence on the results. I don’t really understand why Butterfly_Refinement Region affects the results, which result is more correct? Can you help me?
Thank you for your help.
The following diagram shows the battery connections

The following picture shows the region limited by Butterfly_Refinement Region.

The following graph shows the simulation result with Butterfly_Refinement Region connected.

Here is the simulation result without Butterfly_Refinement Region connected.