This points to a bad memory card, card reader, or USB cable. Lightroom does not damage images this way by itself. The damage is already present in the actual files or caused by the file copy from the memory card. You don't see it initially because the area of the file that has the jpeg preview of your raw image (which is what most apps will show you) is not damaged. However, when Lightroom or Photoshop camera raw ready the image, it runs accross file damage in the raw data area of the file (which is way bigger than the jpeg preview).
Try a new memory card, a different card reader, and a different USB cable.