ImagePullBackOff reported on OpenShift Container Platform 4 with error "unrecognized signature format, starting with binary 0x3c"

Issue

• Image pulls from registry.redhat.io fails with error like below.

  Trying to pull registry.redhat.io/redhat/redhat-operator-index:v4.14...
  WARN[0003] Signature "https://registry.redhat.io/containers/sigstore/redhat/redhat-operator-index@sha256=e1621140d0ca03eba46653325383cc51158a4fa338a55e33634d9329fa6dba12/signature-1" has Content-Type "text/html; charset=UTF-8", unexpected for a signature 
  Error: copying system image from manifest list: Source image rejected: parsing signature https://registry.redhat.io/containers/sigstore/redhat/redhat-operator-index@sha256=e1621140d0ca03eba46653325383cc51158a4fa338a55e33634d9329fa6dba12/signature-1: unrecognized signature format, starting with binary 0x3c
  

• We started seeing problems with Tekton runs earlier today and found the below error reported when Images from registry.redhat.io are being pulled.

  Warning  Failed          14s (x2 over 31s)  kubelet            Failed to pull image "registry.redhat.io/openshift-pipelines/pipelines-entrypoint-rhel8@sha256:8713094dc208c29dc3ed8aeee24b3f11f7cb8ef9bfad94d08dc0cc6a7d80fde6": rpc error: code = Unknown desc = copying system image from manifest list: reading signatures: parsing signature https://registry.redhat.io/containers/sigstore/openshift-pipelines/pipelines-entrypoint-rhel8@sha256=66e585553b1c100f4d4860cdd69c564f5afbeaecf79ab6b0fc56bfa3ec6e89ac/signature-5: unrecognized signature format, starting with binary 0x3c
  

• We are seeing many ImagePullBackOff error for Images from registry.redhat.io with unrecognized signature format, starting with binary 0x3c being reported

• Why do we see problems with Images pulled from registry.redhat.io with unrecognized signature format, starting with binary 0x3c being reported?