why fix the fx and fy when center-crop the image patch in the code?

[Miaosheng1]

hello. when you apply center-crop for the image, I think you should fix the cx and cy for the image intrinsics. But in your implementation, you fix the fx and fy. Is this your implementation bug? https://github.com/donydchen/mvsplat/blob/378ff818c0151719bbc052ac2797a2c769766320/src/dataset/shims/patch_shim.py#L15-L21