It appears it has never been green:
https://github.com/cupy/self-hosted-ci/actions/workflows/ci.yml

This is problematic because it reduces our level of confidence in accepting PRs. A PR can

• implement a backend-agnostic feature/fix (ex: NumPy coverage)
• implement CUDA feature/optimization/fix
• implement ROCm feature/optimization/fix

In any case, a green CI is a good indication that there is no accidental breakage/interference introduced at any point. It would be nice to strive for this goal.