I tried to set the value of the “Forced Lod Model” of the house in the scene to 1 and 4, and the corresponding number of triangles was 3300k and 2300k. The actual number of triangles of the house is 388k in LOD0.
The reason this happens is that not just the main window’s objects(that means all objects) be STAT RHI statistics. That is, when a static mesh window is opened, it is calculated twice(One in scene, one in static mesh window).