Flaky behavior: often getting "Error: cannot read <commit-hash>"

[Ari-Kishon]

Since about a month ago, our job summaries have been flooded with errors from actions/checkout stating that certain commits could not be read.

This seems to happen randomly, and often resolves itself on re-run.
additionally it should be noted that actions checkout is called with "ref: ${{ inputs.ref }}" which may be empty.
providing an empty string seems to checkout the triggering ref

While this error does not cancel the job, it does leave many items in the job summary, burying the actual summary information at the bottom

This occurs on a private repository, using both github and self hosted runners.

feel free to request more information if needed