I’m also experiencing the same issue with Apple ProRAW .dng files not displaying properly. The rainbow effect happens when looking at the entire timeline of pictures. Clicking into the individual image correctly displays the photo.
Were you able to diagnose the problem, and is there a fix?
Short story long, I had hoped that a new version of LibRaw would address the issue, but it didn’t. I then tried Darktable and Rawtherapee’s RAW converter CLIs, and they also couldn’t handle it, so I ended up changing the image rasterizer to be more accepting of embedded JPEGs. Specifically, before the change, the embedded JPEG had to be equivalent to the RAW image resolution, but now we’ll use the embedded PreviewImage as long as the resolution is ~90% of the original.