Mmmm... I'm just thinking (I haven't had time to do anything with this github-action for a while): if it's behind and it can fast-forward I think that it works without the -f. "man git-push" says:

can cause the remote repository to lose commits; use it with care.

Now the github-action can push into a directory (and leave the repository untouched) I think that this might cause problems. This is a new option after you did the PR.

Have you found some flow where you needed the -f?

I only now noticed this PR. I needed a force push for my workflow and created a PR where force pushing is optional (and not default). @cpina If you are maintaining this repo, then I believe my PR supersedes this one

I still need to look into this. Before merging code and adding features / changes I want to write tests to avoid regressions, that's why I haven't actioned it yet.