How does Artifact Registry's vulnerability scanner detect an image's base OS?

[Elkasitu]

Artifact Registry's vulnerability scanner only works with a given set of supported base OS [1], however when trying an image with a supposedly supported base OS, the scanner shows the following error "Failed to identify known supported OS in image". The image in question is based on ubi9 [2] which is functionally the same as RHEL 9 and even the `/etc/os-release` is the same as the rhel9 [3] version of the image.

So how can I know whether my base image will actually be supported?

[1] https://cloud.google.com/artifact-analysis/docs/container-scanning-overview#os

[2] https://catalog.redhat.com/software/containers/ubi9/python-311/63f764b03f0b02a2e2d63fff?architecture...

[3] https://catalog.redhat.com/software/containers/rhel9/python-311/63f764969b0ca19f84f7e7c0?architectur...