app service cannot pull image with format <registry>/<repo>:<tag>@<digest>

Question

Hello App Service folks!

In Web App for Containers, I have determined that these combinations work when specifying the container image

  {
    "name": "DOCKER_CUSTOM_IMAGE_NAME",
    "value": "DOCKER|mcr.microsoft.com/cbl-mariner/base/nginx:1"
  }

  {
    "name": "DOCKER_CUSTOM_IMAGE_NAME",
    "value": "DOCKER|mcr.microsoft.com/cbl-mariner/base/nginx@sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d"
  }

But the following does not: using the <registry>/<repo>:<tag>@<digest> which is understood by Docker CLI

  {
    "name": "DOCKER_CUSTOM_IMAGE_NAME",
    "value": "DOCKER|mcr.microsoft.com/cbl-mariner/base/nginx:1@sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d"
  }

I was wondering, if the above is possible, and I just need to escape something to make it work.

Thanks in advance,
Rick

PS: Below shows me using docker pull to include the tag, and the digest:

docker pull mcr.microsoft.com/cbl-mariner/base/nginx:1@sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d
mcr.microsoft.com/cbl-mariner/base/nginx@sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d: 
Pulling from cbl-mariner/base/nginx
Digest: sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d
Status: Image is up to date for mcr.microsoft.com/cbl-mariner/base/nginx@sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d
mcr.microsoft.com/cbl-mariner/base/nginx:1@sha256:49e78168eb77857195403e8a613a24b524e96e0d8f89a8947b0805d389d0918d