unexpected result of pcl::SACsegmentation

Win 11 Pro PCL 1.12.1 Visual Studio

I want to segment a plane within point cloud using SACsegmentation module and get some unexpected result. Though I solve this problem then, I want to know the reason causing the problem. I want to segment the ground(as blue line set showed), but the code returns the gross one as showed with red lines. enter image description here here is the code and pcd file. https://github.com/PointCloudLibrary/pcl/files/8101342/compress.zip And after sampling down the point cloud with UniformSample module, it generates the right result. Is it possible that the size of point cloud has some influence