When I execute the following two tag commands in a row on OCP 4.14.0-ec.3, Multi-Arch:

  oc tag $IMAGE@$DIGEST_MANIFEST test-1:tag-manifest
  sleep 0
  oc tag $IMAGE@$DIGEST_MANIFEST test-1:tag-manifest-preserve-original --import-mode=PreserveOriginal

Then wrong data is written to the .image.dockerImageMetadata record.
If there is a delay between these two commands, e.g. sleep 5, then the image.dockerImageMetadata contains correct data.

Run the below script and you see the error. If you change the SLEEP_TIME=5, then the script passes. No problem.

#!/usr/bin/env bash
set -e
SLEEP_TIME=0     # Test will fail, when sleep time is 0, use delay of 3 sec or more to pass this test

IMAGE="quay.io/podman/hello"
podman pull $IMAGE:latest
DIGEST_MANIFEST=$(podman inspect quay.io/podman/hello:latest | jq -r '.[0].Digest')

oc new-project "ir-test-001"
oc create imagestream test-1
oc import-image test-1 --from="${IMAGE}@${DIGEST_MANIFEST}" --import-mode='PreserveOriginal'

oc tag $IMAGE@$DIGEST_MANIFEST test-1:tag-manifest
sleep "${SLEEP_TIME}"
oc tag $IMAGE@$DIGEST_MANIFEST test-1:tag-manifest-preserve-original --import-mode=PreserveOriginal

sleep 5

[[ $(oc get istag test-1:tag-manifest-preserve-original -o json | jq -r '.image.dockerImageMetadata.Architecture') == "null" ]] && echo "pass: tag-manifest-preserve-original has no architecture" || echo "fail: tag-preserve-original has architecture and should not"

fail: tag-preserve-original has architecture and should not

oc get istag test-1:tag-manifest-preserve-original -o json | jq -r '.image.dockerImageMetadata.Architecture'
amd64

pass: tag-manifest-preserve-original has no architecture

oc get istag test-1:tag-manifest-preserve-original -o json | jq -r '.image.dockerImageMetadata.Architecture'
null

This was tested with OC command on x86_64