How to reference artifact generated by pre-commit pipeline in the post-commit / upon merge request pipeline

It is a ‘special’ workflow. User pushes a commit, the CI pipeline runs, generates some build artifacts. I want to uniquely reference those artifacts in the post-commit pipeline i.e the one running after the merge request been approved and merged.
How do I achieve something like this? I understand I can use variables as name for an artifact, but still cannot figure out what to use to give me this unique relationship?!