What's special about is that it kind of fails the E2E test. Apple keeps a lot of metadata available to themselves, including but not limited to: filenames, checksums before encryption, file type (from e.g. magic bytes so that a PNG called stuff.txt won't fool them), creation, modification and access timestamps and access counters. It's also seems that files are encrypted using their own checksums as the key (so Apple can de-duplicate files).
So I'm not sure what LEO's are worried about, the metadata available to them from Apple is more than enough for most of their needs.
What's special about is that it kind of fails the E2E test. Apple keeps a lot of metadata available to themselves, including but not limited to: filenames, checksums before encryption, file type (from e.g. magic bytes so that a PNG called stuff.txt won't fool them), creation, modification and access timestamps and access counters. It's also seems that files are encrypted using their own checksums as the key (so Apple can de-duplicate files).
So I'm not sure what LEO's are worried about, the metadata available to them from Apple is more than enough for most of their needs.