In the operator image /helm-charts/apicurito/values.yaml there is:

# Image: Docker project with apicurito image, see apicurito build documentation for more details
image: apicurio/apicurito-ui

that should point to the prod version with the redhat.registry.io repository (something like registry.redhat.io/fuse7/fuse-apicurito:1.3-3 at the moment)