A new feature in v4 of download-artifact is the ability to download all artifacts from a workflow run. The artifact name below causes issues when trying to download all the artifacts:

let dockerbuildFilename = `${GitHub.context.repo.owner}~${GitHub.context.repo.repo}~${refs[0].substring(0, 6).toUpperCase()}`;

I believe the issue is the ~ character and I propose that it be changed to a -.