Inspecting a Docker BuildKit cache on registry

The docker buildx build command accepts an option --cache-to type=registry,ref=my/repo:buildcache that pushes the build cache to the registry (some docs).

How can this cache be inspected?

• docker buildx imagetools inspect my/repo:buildcache crashes from a null pointer dereference.

• docker manifest inspect my/repo:buildcache triggers a 500 Internal Server Error.

• The Docker Hub website provides no information about a tag for a pushed build cache, except that it exists.

If I run a build with the symmetric --cache-from type=registry,ref=my/repo:buildcache option, it does print importing cache manifest from my/repo:buildcache but I don't know what it has imported.